Cfrgtkky

How can we change any of the two dots of the ddots math symbol?

I can change both of them:

documentclass{article}



usepackage{xcolor}



begin{document}



$color{red}ddot{color{black}x}$



end{document}

Something like:

The following uses two slightly shifted coloured dot macros. The placement is not perfect and might be really bad for some letters.

documentclass{article}



% for colours

usepackage{xcolor}

% for mighty interface to define new macros, it also loads the l3 kernel

usepackage{xparse}

% for mathrlap

usepackage{mathtools}



% change to the coding language of LaTeX3 (in which spaces are ignored, that why

% I can do stuff like { #2 } etc., also _ is a character now and can be part of

% macro names)

ExplSyntaxOn

% define a user facing macro, it takes one optional argument, which by default

% is empty and a mandatory one (neither of them can contain a par). The

% optional argument will be split at a "," once.

NewDocumentCommand cddot { >{SplitArgument{1}{,}}O{} m }

  {

    % pass on the now split argument #1 and the mandatory argument #2. #1 will

    % be something like { #1.1 } { #1.2 }

    __manooooh_cddot:nnn #1 { #2 }

  }

% define a new internal macro (cs_new_protected:Npn is like protecteddef)

cs_new_protected:Npn __manooooh_cddot:nnn #1 #2 #3

  {

    % start a new group

    group_begin:

    % check whether the first argument is blank (meaning it only contains spaces

    % or nothing), if it isn't blank change the color. It will be blank if you

    % don't use an optional argument or if you start your optional argument with

    % a ","

    tl_if_blank:nF { #1 } { color { #1 } }

    % mathrlap will print its argument without really taking any space, phantom

    % will only take the space of #3, mkern-1.5mu will move the dot slightly to

    % the left

    mathrlap { mkern-1.25mu dot { phantom { #3 } } }

    % end the group containing the first color

    group_end:

    % start a new group

    group_begin:

    % IfValueT will check whether the second part of the split argument was

    % available (so will result in True if there was a comma in [#1]). If there

    % was a second argument assume it is the second color

    IfValueT { #2 } { color { #2 } }

    % again mathrlap and a phantom #3, this time shifting the dot slightly to

    % the right by 2mu

    mathrlap { mkern+2.25mu dot { phantom { #3 } } }

    % end the second color's group

    group_end:

    % print #3 without further ado (since we used mathrlap previously we're

    % still on the same spot and due to the phantom #3 will only be printed

    % visible once

    #3

  }

% end the LaTeX3 programming syntax

ExplSyntaxOff



begin{document}

% without optional argument

$cddot{x}$



% with the first half of the optional argument

$cddot[blue]{x}$



% with the second half of the optional argument

$cddot[,green]{x}$



% with both halves of the optional argument

$cddot[blue,green]{x}$



% for comparison

$ddot{x}$

end{document}

Adapting from the definition of dddot in amsmath. The bottom line in the picture shows the symbol superimposed on each other; the difference is really negligible.

documentclass{article}

usepackage{amsmath}

usepackage{xcolor}



makeatletter

DeclareRobustCommand{colorddot}[3]{%

  % #1=color of first dot, #2=color of second dot, #3=accentee

  {mathop{kernz@#3}limits^{%

    vbox to-1.55ex@{%

      kern-tw@ex@

      hbox{normalfontkern0.05emtextcolor{#1}{.}kern-0.085emtextcolor{#2}{.}}

      vss

    }%

  }}%

}

makeatother



begin{document}



$ddot{x}$



$colorddot{green}{blue}{x}$



$ddot{x}$llap{$colorddot{green}{blue}{x}$}

$colorddot{green}{blue}{x}$llap{$ddot{x}$}



end{document}

Beware that the different colors will make the dots to appear misaligned.

One may just use the accents package, which was made for this.

documentclass{article}

usepackage{amsmath}

usepackage{accents}

usepackage{pgffor}

usepackage{xcolor}

newcommand{ColorDots}[2]{accentset{foreach X in {#1}

{textcolor{X}{boldsymbol{.}}}}{#2}}

begin{document}

$accentset{boldsymbol{..}}{x}$ $ColorDots{red,blue}{y}$ $ColorDots{red}{z}$

$ColorDots{red,orange,blue}{X}$

end{document}