Why is there a trace line in this tikz graph?












8














I am trying to generate a shaded area between three curves: two are
y=±√x and third one is y=5.



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, intersection segments={of=p1 and p3,sequence=L2 -- R1}];
path [name path=right, intersection segments={of=p2 and p3,sequence=L1 -- R2}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


generated image, notice the pointed trace










share|improve this question




















  • 5




    Welcome to TeX.SE! With that nick name you will feel at home here!
    – CarLaTeX
    Dec 1 '18 at 14:52










  • Please provide a complete MWE (with preamble and all of that stuff) that can be compiled by others. This increases the chance of people offering their help.
    – Raven
    Dec 1 '18 at 14:58






  • 2




    @marmot, OP is asking about the dotted thin line connecting the cuspid and B point. It is very light.
    – Sigur
    Dec 1 '18 at 15:09










  • also notice how the seemingly dotted line fades away from y=0 to y=5. It is my conjecture that it is not a dotted line but rather a reminiscent of rounding-off error while computing the inverse or the intersections. I'll wait for expert opinions on it. But it would also be helpful if others can recreate and confirm the issue.
    – rubber duck
    Dec 1 '18 at 15:16
















8














I am trying to generate a shaded area between three curves: two are
y=±√x and third one is y=5.



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, intersection segments={of=p1 and p3,sequence=L2 -- R1}];
path [name path=right, intersection segments={of=p2 and p3,sequence=L1 -- R2}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


generated image, notice the pointed trace










share|improve this question




















  • 5




    Welcome to TeX.SE! With that nick name you will feel at home here!
    – CarLaTeX
    Dec 1 '18 at 14:52










  • Please provide a complete MWE (with preamble and all of that stuff) that can be compiled by others. This increases the chance of people offering their help.
    – Raven
    Dec 1 '18 at 14:58






  • 2




    @marmot, OP is asking about the dotted thin line connecting the cuspid and B point. It is very light.
    – Sigur
    Dec 1 '18 at 15:09










  • also notice how the seemingly dotted line fades away from y=0 to y=5. It is my conjecture that it is not a dotted line but rather a reminiscent of rounding-off error while computing the inverse or the intersections. I'll wait for expert opinions on it. But it would also be helpful if others can recreate and confirm the issue.
    – rubber duck
    Dec 1 '18 at 15:16














8












8








8


1





I am trying to generate a shaded area between three curves: two are
y=±√x and third one is y=5.



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, intersection segments={of=p1 and p3,sequence=L2 -- R1}];
path [name path=right, intersection segments={of=p2 and p3,sequence=L1 -- R2}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


generated image, notice the pointed trace










share|improve this question















I am trying to generate a shaded area between three curves: two are
y=±√x and third one is y=5.



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, intersection segments={of=p1 and p3,sequence=L2 -- R1}];
path [name path=right, intersection segments={of=p2 and p3,sequence=L1 -- R2}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


generated image, notice the pointed trace







tikz-pgf pgfplots shading tikz-graphs mathematics






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Dec 1 '18 at 15:03

























asked Dec 1 '18 at 14:49









rubber duck

433




433








  • 5




    Welcome to TeX.SE! With that nick name you will feel at home here!
    – CarLaTeX
    Dec 1 '18 at 14:52










  • Please provide a complete MWE (with preamble and all of that stuff) that can be compiled by others. This increases the chance of people offering their help.
    – Raven
    Dec 1 '18 at 14:58






  • 2




    @marmot, OP is asking about the dotted thin line connecting the cuspid and B point. It is very light.
    – Sigur
    Dec 1 '18 at 15:09










  • also notice how the seemingly dotted line fades away from y=0 to y=5. It is my conjecture that it is not a dotted line but rather a reminiscent of rounding-off error while computing the inverse or the intersections. I'll wait for expert opinions on it. But it would also be helpful if others can recreate and confirm the issue.
    – rubber duck
    Dec 1 '18 at 15:16














  • 5




    Welcome to TeX.SE! With that nick name you will feel at home here!
    – CarLaTeX
    Dec 1 '18 at 14:52










  • Please provide a complete MWE (with preamble and all of that stuff) that can be compiled by others. This increases the chance of people offering their help.
    – Raven
    Dec 1 '18 at 14:58






  • 2




    @marmot, OP is asking about the dotted thin line connecting the cuspid and B point. It is very light.
    – Sigur
    Dec 1 '18 at 15:09










  • also notice how the seemingly dotted line fades away from y=0 to y=5. It is my conjecture that it is not a dotted line but rather a reminiscent of rounding-off error while computing the inverse or the intersections. I'll wait for expert opinions on it. But it would also be helpful if others can recreate and confirm the issue.
    – rubber duck
    Dec 1 '18 at 15:16








5




5




Welcome to TeX.SE! With that nick name you will feel at home here!
– CarLaTeX
Dec 1 '18 at 14:52




Welcome to TeX.SE! With that nick name you will feel at home here!
– CarLaTeX
Dec 1 '18 at 14:52












Please provide a complete MWE (with preamble and all of that stuff) that can be compiled by others. This increases the chance of people offering their help.
– Raven
Dec 1 '18 at 14:58




Please provide a complete MWE (with preamble and all of that stuff) that can be compiled by others. This increases the chance of people offering their help.
– Raven
Dec 1 '18 at 14:58




2




2




@marmot, OP is asking about the dotted thin line connecting the cuspid and B point. It is very light.
– Sigur
Dec 1 '18 at 15:09




@marmot, OP is asking about the dotted thin line connecting the cuspid and B point. It is very light.
– Sigur
Dec 1 '18 at 15:09












also notice how the seemingly dotted line fades away from y=0 to y=5. It is my conjecture that it is not a dotted line but rather a reminiscent of rounding-off error while computing the inverse or the intersections. I'll wait for expert opinions on it. But it would also be helpful if others can recreate and confirm the issue.
– rubber duck
Dec 1 '18 at 15:16




also notice how the seemingly dotted line fades away from y=0 to y=5. It is my conjecture that it is not a dotted line but rather a reminiscent of rounding-off error while computing the inverse or the intersections. I'll wait for expert opinions on it. But it would also be helpful if others can recreate and confirm the issue.
– rubber duck
Dec 1 '18 at 15:16










2 Answers
2






active

oldest

votes


















12














Big thanks to Sigur for explaining the question to me! The issue is that the paths do not have the appropriate orientation. So I had to reorder the sequences and reverse one to get



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, intersection segments={of=p1 and p3,sequence={R1[reverse] -- L2}}];
path [name path=right,
intersection segments={of=p2 and p3,sequence={L1 -- R2}}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



How can one debug this? Just draw these paths with arrows.



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2 -- R1}];
path [name path=right, thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1 -- R2}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



This reveals that the left path is a loop, which explains the faint dots on the left. It is a loop because you run through the curved part from top left to bottom right and then through the horizontal part.



This also shows that the horizontal curve is not at all necessary here, for the fills, you could just do



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, %thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2}];
path [name path=right, %thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


to get the first output above.






share|improve this answer



















  • 2




    Amazing explanation. Incredible how some miracles could appear in LaTeX life!!
    – Sigur
    Dec 1 '18 at 17:51






  • 1




    @Sigur Your comment seems to imply that there is a life without LaTeX. Really? ;-)
    – marmot
    Dec 1 '18 at 17:56






  • 1




    Well, at least sometimes I move to a parallel life, Python life!!! lol
    – Sigur
    Dec 1 '18 at 17:58



















1














in your particular cae you can define single path for curve sqrt(abs(x)) and with this somehow simplify diagram code:



documentclass[margin=3.141592]{standalone}
usepackage{pgfplots}
pgfplotsset{compat=1.16}
usepgfplotslibrary{fillbetween}
usetikzlibrary{intersections, patterns}

begin{document}
begin{tikzpicture}[lbl/.style={font=footnotesize,text=blue}]
begin{axis}[grid,
%axis equal=false,
xmin=-30, xmax=30,
ymin=-.5, ymax=6,
minor tick num=1,
axis lines = middle,
tick label style={inner sep=2pt, font=footnotesize},
%
every axis plot post/.append style={thick},
samples=100
]
addplot [draw=none,domain=-30:30,
name path=p1] {sqrt(abs(x))};
addplot [dashed, name path=p3,
every mark/.append style={solid,scale=1.2},
mark=*] coordinates {(-25,5) (25,5)}
node [pos=0,lbl, above right] {$B=(-25,5)$}
node [pos=1,lbl, above left] {$A=( 25,5)$};
addplot [pattern=north east lines,
pattern color=blue,opacity=.8]
fill between [of=p1 and p3];
%
addplot [dashed,domain=-30:0] {sqrt(abs(x))};
addplot [ domain= 0:30] {sqrt(abs(x))};
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


which gives:



enter image description here






share|improve this answer





















  • If you really want to simplify things here, just kick out all the fillbetween and name path stuff, and just do addplot [draw=none,domain=-30:30,pattern=north east lines,pattern color=blue,domain=-25:25] {sqrt(abs(x))};. However, I thought this was not the point of the question.
    – marmot
    Dec 1 '18 at 20:05










  • @marmot, as i understood the question, the point is remove doted line between point B and coordinate origin. and yes, your suggestion (with deleted domain=-30:30) gives even shorter code with desired result. however your code is real "miracle" (+1) and probably useful in more generalized cases when you can not use simpler solution mentioned in your comment above.
    – Zarko
    Dec 1 '18 at 20:19













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2 Answers
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active

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2 Answers
2






active

oldest

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active

oldest

votes






active

oldest

votes









12














Big thanks to Sigur for explaining the question to me! The issue is that the paths do not have the appropriate orientation. So I had to reorder the sequences and reverse one to get



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, intersection segments={of=p1 and p3,sequence={R1[reverse] -- L2}}];
path [name path=right,
intersection segments={of=p2 and p3,sequence={L1 -- R2}}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



How can one debug this? Just draw these paths with arrows.



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2 -- R1}];
path [name path=right, thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1 -- R2}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



This reveals that the left path is a loop, which explains the faint dots on the left. It is a loop because you run through the curved part from top left to bottom right and then through the horizontal part.



This also shows that the horizontal curve is not at all necessary here, for the fills, you could just do



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, %thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2}];
path [name path=right, %thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


to get the first output above.






share|improve this answer



















  • 2




    Amazing explanation. Incredible how some miracles could appear in LaTeX life!!
    – Sigur
    Dec 1 '18 at 17:51






  • 1




    @Sigur Your comment seems to imply that there is a life without LaTeX. Really? ;-)
    – marmot
    Dec 1 '18 at 17:56






  • 1




    Well, at least sometimes I move to a parallel life, Python life!!! lol
    – Sigur
    Dec 1 '18 at 17:58
















12














Big thanks to Sigur for explaining the question to me! The issue is that the paths do not have the appropriate orientation. So I had to reorder the sequences and reverse one to get



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, intersection segments={of=p1 and p3,sequence={R1[reverse] -- L2}}];
path [name path=right,
intersection segments={of=p2 and p3,sequence={L1 -- R2}}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



How can one debug this? Just draw these paths with arrows.



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2 -- R1}];
path [name path=right, thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1 -- R2}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



This reveals that the left path is a loop, which explains the faint dots on the left. It is a loop because you run through the curved part from top left to bottom right and then through the horizontal part.



This also shows that the horizontal curve is not at all necessary here, for the fills, you could just do



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, %thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2}];
path [name path=right, %thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


to get the first output above.






share|improve this answer



















  • 2




    Amazing explanation. Incredible how some miracles could appear in LaTeX life!!
    – Sigur
    Dec 1 '18 at 17:51






  • 1




    @Sigur Your comment seems to imply that there is a life without LaTeX. Really? ;-)
    – marmot
    Dec 1 '18 at 17:56






  • 1




    Well, at least sometimes I move to a parallel life, Python life!!! lol
    – Sigur
    Dec 1 '18 at 17:58














12












12








12






Big thanks to Sigur for explaining the question to me! The issue is that the paths do not have the appropriate orientation. So I had to reorder the sequences and reverse one to get



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, intersection segments={of=p1 and p3,sequence={R1[reverse] -- L2}}];
path [name path=right,
intersection segments={of=p2 and p3,sequence={L1 -- R2}}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



How can one debug this? Just draw these paths with arrows.



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2 -- R1}];
path [name path=right, thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1 -- R2}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



This reveals that the left path is a loop, which explains the faint dots on the left. It is a loop because you run through the curved part from top left to bottom right and then through the horizontal part.



This also shows that the horizontal curve is not at all necessary here, for the fills, you could just do



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, %thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2}];
path [name path=right, %thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


to get the first output above.






share|improve this answer














Big thanks to Sigur for explaining the question to me! The issue is that the paths do not have the appropriate orientation. So I had to reorder the sequences and reverse one to get



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, intersection segments={of=p1 and p3,sequence={R1[reverse] -- L2}}];
path [name path=right,
intersection segments={of=p2 and p3,sequence={L1 -- R2}}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



How can one debug this? Just draw these paths with arrows.



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2 -- R1}];
path [name path=right, thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1 -- R2}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


enter image description here



This reveals that the left path is a loop, which explains the faint dots on the left. It is a loop because you run through the curved part from top left to bottom right and then through the horizontal part.



This also shows that the horizontal curve is not at all necessary here, for the fills, you could just do



documentclass[10pt,multi=False,border=5pt,tikz,class=scrartcl]{standalone}
usepackage{xcolor}

usepackage{pgfplots}
pgfplotsset{compat=newest}
usetikzlibrary{arrows.meta}
usetikzlibrary{patterns}
usepgfplotslibrary{fillbetween}
begin{document}
begin{tikzpicture}
begin{axis}[grid=both, axis equal=false, ymin=-1, ymax=6, xmin=-30, xmax=30,
minor tick num=1,axis lines = middle,
label style={font=small,at={(ticklabel cs:1.1)}},
tick label style={font=footnotesize}]
addplot [thick,dashed,samples=50, domain=-30:0,name path=p1] {sqrt(abs(x))};
addplot [thick,samples=50, domain=0:30,name path=p2] {sqrt(abs(x))};
addplot [thick,dashed,name path=p3] coordinates {(-25,5) (25,5)};
path [name path=left, %thick,draw=blue,-latex,
intersection segments={of=p1 and p3,sequence=L2}];
path [name path=right, %thick,draw=red,-latex,
intersection segments={of=p2 and p3,sequence=L1}];
addplot [pattern=north east lines,pattern color=blue,opacity=.8] fill between [
of=left and right,reverse=false];
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
addplot+ [only marks,mark=*] coordinates { (-25,5) (25,5)}
node [pos=0,above right] {footnotesizetextcolor{blue}{$B=(-25,5)$}}
node [pos=1,above left] {footnotesizetextcolor{blue}{$A=(25,5)$}};
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


to get the first output above.







share|improve this answer














share|improve this answer



share|improve this answer








edited Dec 1 '18 at 15:22

























answered Dec 1 '18 at 15:16









marmot

87.7k4101189




87.7k4101189








  • 2




    Amazing explanation. Incredible how some miracles could appear in LaTeX life!!
    – Sigur
    Dec 1 '18 at 17:51






  • 1




    @Sigur Your comment seems to imply that there is a life without LaTeX. Really? ;-)
    – marmot
    Dec 1 '18 at 17:56






  • 1




    Well, at least sometimes I move to a parallel life, Python life!!! lol
    – Sigur
    Dec 1 '18 at 17:58














  • 2




    Amazing explanation. Incredible how some miracles could appear in LaTeX life!!
    – Sigur
    Dec 1 '18 at 17:51






  • 1




    @Sigur Your comment seems to imply that there is a life without LaTeX. Really? ;-)
    – marmot
    Dec 1 '18 at 17:56






  • 1




    Well, at least sometimes I move to a parallel life, Python life!!! lol
    – Sigur
    Dec 1 '18 at 17:58








2




2




Amazing explanation. Incredible how some miracles could appear in LaTeX life!!
– Sigur
Dec 1 '18 at 17:51




Amazing explanation. Incredible how some miracles could appear in LaTeX life!!
– Sigur
Dec 1 '18 at 17:51




1




1




@Sigur Your comment seems to imply that there is a life without LaTeX. Really? ;-)
– marmot
Dec 1 '18 at 17:56




@Sigur Your comment seems to imply that there is a life without LaTeX. Really? ;-)
– marmot
Dec 1 '18 at 17:56




1




1




Well, at least sometimes I move to a parallel life, Python life!!! lol
– Sigur
Dec 1 '18 at 17:58




Well, at least sometimes I move to a parallel life, Python life!!! lol
– Sigur
Dec 1 '18 at 17:58











1














in your particular cae you can define single path for curve sqrt(abs(x)) and with this somehow simplify diagram code:



documentclass[margin=3.141592]{standalone}
usepackage{pgfplots}
pgfplotsset{compat=1.16}
usepgfplotslibrary{fillbetween}
usetikzlibrary{intersections, patterns}

begin{document}
begin{tikzpicture}[lbl/.style={font=footnotesize,text=blue}]
begin{axis}[grid,
%axis equal=false,
xmin=-30, xmax=30,
ymin=-.5, ymax=6,
minor tick num=1,
axis lines = middle,
tick label style={inner sep=2pt, font=footnotesize},
%
every axis plot post/.append style={thick},
samples=100
]
addplot [draw=none,domain=-30:30,
name path=p1] {sqrt(abs(x))};
addplot [dashed, name path=p3,
every mark/.append style={solid,scale=1.2},
mark=*] coordinates {(-25,5) (25,5)}
node [pos=0,lbl, above right] {$B=(-25,5)$}
node [pos=1,lbl, above left] {$A=( 25,5)$};
addplot [pattern=north east lines,
pattern color=blue,opacity=.8]
fill between [of=p1 and p3];
%
addplot [dashed,domain=-30:0] {sqrt(abs(x))};
addplot [ domain= 0:30] {sqrt(abs(x))};
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


which gives:



enter image description here






share|improve this answer





















  • If you really want to simplify things here, just kick out all the fillbetween and name path stuff, and just do addplot [draw=none,domain=-30:30,pattern=north east lines,pattern color=blue,domain=-25:25] {sqrt(abs(x))};. However, I thought this was not the point of the question.
    – marmot
    Dec 1 '18 at 20:05










  • @marmot, as i understood the question, the point is remove doted line between point B and coordinate origin. and yes, your suggestion (with deleted domain=-30:30) gives even shorter code with desired result. however your code is real "miracle" (+1) and probably useful in more generalized cases when you can not use simpler solution mentioned in your comment above.
    – Zarko
    Dec 1 '18 at 20:19


















1














in your particular cae you can define single path for curve sqrt(abs(x)) and with this somehow simplify diagram code:



documentclass[margin=3.141592]{standalone}
usepackage{pgfplots}
pgfplotsset{compat=1.16}
usepgfplotslibrary{fillbetween}
usetikzlibrary{intersections, patterns}

begin{document}
begin{tikzpicture}[lbl/.style={font=footnotesize,text=blue}]
begin{axis}[grid,
%axis equal=false,
xmin=-30, xmax=30,
ymin=-.5, ymax=6,
minor tick num=1,
axis lines = middle,
tick label style={inner sep=2pt, font=footnotesize},
%
every axis plot post/.append style={thick},
samples=100
]
addplot [draw=none,domain=-30:30,
name path=p1] {sqrt(abs(x))};
addplot [dashed, name path=p3,
every mark/.append style={solid,scale=1.2},
mark=*] coordinates {(-25,5) (25,5)}
node [pos=0,lbl, above right] {$B=(-25,5)$}
node [pos=1,lbl, above left] {$A=( 25,5)$};
addplot [pattern=north east lines,
pattern color=blue,opacity=.8]
fill between [of=p1 and p3];
%
addplot [dashed,domain=-30:0] {sqrt(abs(x))};
addplot [ domain= 0:30] {sqrt(abs(x))};
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


which gives:



enter image description here






share|improve this answer





















  • If you really want to simplify things here, just kick out all the fillbetween and name path stuff, and just do addplot [draw=none,domain=-30:30,pattern=north east lines,pattern color=blue,domain=-25:25] {sqrt(abs(x))};. However, I thought this was not the point of the question.
    – marmot
    Dec 1 '18 at 20:05










  • @marmot, as i understood the question, the point is remove doted line between point B and coordinate origin. and yes, your suggestion (with deleted domain=-30:30) gives even shorter code with desired result. however your code is real "miracle" (+1) and probably useful in more generalized cases when you can not use simpler solution mentioned in your comment above.
    – Zarko
    Dec 1 '18 at 20:19
















1












1








1






in your particular cae you can define single path for curve sqrt(abs(x)) and with this somehow simplify diagram code:



documentclass[margin=3.141592]{standalone}
usepackage{pgfplots}
pgfplotsset{compat=1.16}
usepgfplotslibrary{fillbetween}
usetikzlibrary{intersections, patterns}

begin{document}
begin{tikzpicture}[lbl/.style={font=footnotesize,text=blue}]
begin{axis}[grid,
%axis equal=false,
xmin=-30, xmax=30,
ymin=-.5, ymax=6,
minor tick num=1,
axis lines = middle,
tick label style={inner sep=2pt, font=footnotesize},
%
every axis plot post/.append style={thick},
samples=100
]
addplot [draw=none,domain=-30:30,
name path=p1] {sqrt(abs(x))};
addplot [dashed, name path=p3,
every mark/.append style={solid,scale=1.2},
mark=*] coordinates {(-25,5) (25,5)}
node [pos=0,lbl, above right] {$B=(-25,5)$}
node [pos=1,lbl, above left] {$A=( 25,5)$};
addplot [pattern=north east lines,
pattern color=blue,opacity=.8]
fill between [of=p1 and p3];
%
addplot [dashed,domain=-30:0] {sqrt(abs(x))};
addplot [ domain= 0:30] {sqrt(abs(x))};
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


which gives:



enter image description here






share|improve this answer












in your particular cae you can define single path for curve sqrt(abs(x)) and with this somehow simplify diagram code:



documentclass[margin=3.141592]{standalone}
usepackage{pgfplots}
pgfplotsset{compat=1.16}
usepgfplotslibrary{fillbetween}
usetikzlibrary{intersections, patterns}

begin{document}
begin{tikzpicture}[lbl/.style={font=footnotesize,text=blue}]
begin{axis}[grid,
%axis equal=false,
xmin=-30, xmax=30,
ymin=-.5, ymax=6,
minor tick num=1,
axis lines = middle,
tick label style={inner sep=2pt, font=footnotesize},
%
every axis plot post/.append style={thick},
samples=100
]
addplot [draw=none,domain=-30:30,
name path=p1] {sqrt(abs(x))};
addplot [dashed, name path=p3,
every mark/.append style={solid,scale=1.2},
mark=*] coordinates {(-25,5) (25,5)}
node [pos=0,lbl, above right] {$B=(-25,5)$}
node [pos=1,lbl, above left] {$A=( 25,5)$};
addplot [pattern=north east lines,
pattern color=blue,opacity=.8]
fill between [of=p1 and p3];
%
addplot [dashed,domain=-30:0] {sqrt(abs(x))};
addplot [ domain= 0:30] {sqrt(abs(x))};
draw [fill=gray,opacity=.5] (0,3.5) ellipse [x radius=12.25, y radius=.1];
node [right] at (11,3) {$r=x=y^2$};
end{axis}
end{tikzpicture}
end{document}


which gives:



enter image description here







share|improve this answer












share|improve this answer



share|improve this answer










answered Dec 1 '18 at 19:34









Zarko

121k865156




121k865156












  • If you really want to simplify things here, just kick out all the fillbetween and name path stuff, and just do addplot [draw=none,domain=-30:30,pattern=north east lines,pattern color=blue,domain=-25:25] {sqrt(abs(x))};. However, I thought this was not the point of the question.
    – marmot
    Dec 1 '18 at 20:05










  • @marmot, as i understood the question, the point is remove doted line between point B and coordinate origin. and yes, your suggestion (with deleted domain=-30:30) gives even shorter code with desired result. however your code is real "miracle" (+1) and probably useful in more generalized cases when you can not use simpler solution mentioned in your comment above.
    – Zarko
    Dec 1 '18 at 20:19




















  • If you really want to simplify things here, just kick out all the fillbetween and name path stuff, and just do addplot [draw=none,domain=-30:30,pattern=north east lines,pattern color=blue,domain=-25:25] {sqrt(abs(x))};. However, I thought this was not the point of the question.
    – marmot
    Dec 1 '18 at 20:05










  • @marmot, as i understood the question, the point is remove doted line between point B and coordinate origin. and yes, your suggestion (with deleted domain=-30:30) gives even shorter code with desired result. however your code is real "miracle" (+1) and probably useful in more generalized cases when you can not use simpler solution mentioned in your comment above.
    – Zarko
    Dec 1 '18 at 20:19


















If you really want to simplify things here, just kick out all the fillbetween and name path stuff, and just do addplot [draw=none,domain=-30:30,pattern=north east lines,pattern color=blue,domain=-25:25] {sqrt(abs(x))};. However, I thought this was not the point of the question.
– marmot
Dec 1 '18 at 20:05




If you really want to simplify things here, just kick out all the fillbetween and name path stuff, and just do addplot [draw=none,domain=-30:30,pattern=north east lines,pattern color=blue,domain=-25:25] {sqrt(abs(x))};. However, I thought this was not the point of the question.
– marmot
Dec 1 '18 at 20:05












@marmot, as i understood the question, the point is remove doted line between point B and coordinate origin. and yes, your suggestion (with deleted domain=-30:30) gives even shorter code with desired result. however your code is real "miracle" (+1) and probably useful in more generalized cases when you can not use simpler solution mentioned in your comment above.
– Zarko
Dec 1 '18 at 20:19






@marmot, as i understood the question, the point is remove doted line between point B and coordinate origin. and yes, your suggestion (with deleted domain=-30:30) gives even shorter code with desired result. however your code is real "miracle" (+1) and probably useful in more generalized cases when you can not use simpler solution mentioned in your comment above.
– Zarko
Dec 1 '18 at 20:19




















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