Construct a polynomial $p$ of degree $leq n-1$ such that $p(a_i) = b_i$











up vote
1
down vote

favorite













Theorem. Given two countably infinite sequences of complex numbers ${a_{n}}_{n}$ and ${b_{n}}_{n}$ with $lim_{n to infty}|a_{n}| = infty$, it is always possible to find a entire function $F$ that satisfies $F(a_{n}) = b_{n}$ for all $n$.




First, I want to prove




Problem. If $a_1,dots,a_n$ and $b_1,dots,b_n$ are distinct complex numbers, I can construct a polynomial $p$ of degree $leq n-1$ such that $p(a_i) = b_i$ for all $i=1,dots,n$.




My approach.



$$c_{0} + c_{1}a_{1} + c_{2}a_{1}^{2} + cdots + c_{n-1}a_{1}^{n-1} = b_{1}$$
$$c_{0} + c_{1}a_{2} + c_{2}a_{2}^{2} + cdots + c_{n-1}a_{2}^{n-1} = b_{2}$$
$$vdots$$
$$c_{0} + c_{1}a_{n} + c_{2}a_{n}^{2} + cdots + c_{n-1}a_{n}^{n-1} = b_{n}$$
and so
$$left(begin{array}{ccccc}
1 & a_{1} & a_{1}^{2} & cdots & a_{1}^{n-1}\
1 & a_{2} & a_{2}^{2} & cdots & a_{2}^{n-1}\
vdots & vdots & vdots & ddots & vdots\
1 & a_{n} & a_{n}^{2} & cdots & a_{n}^{n-1}\
end{array}right)
left(begin{array}{c}
c_{0}\
c_{1}\
vdots\
c_{n-1}
end{array}right)
=
left(begin{array}{c}
b_{1}\
b_{2}\
vdots\
b_{n}
end{array}right)$$



What is the best method to solve this system? Or, Is there a better approach to this problem??










share|cite|improve this question


















  • 2




    This is called lagrange interpolation.
    – Robert Wolfe
    Nov 19 at 3:45










  • @RobertWolfe, thank you!
    – Lucas Corrêa
    Nov 19 at 3:49






  • 2




    Just like magic - if you the name of something, you gain power.
    – marty cohen
    Nov 19 at 4:20






  • 1




    For the main question see "An Interpoation Problem' in Rudin's RCA. [ Chapter on Zeros of Holomorphic Functions].
    – Kavi Rama Murthy
    Nov 19 at 5:28












  • @martycohen, absolutely! hahaha
    – Lucas Corrêa
    Nov 19 at 16:54















up vote
1
down vote

favorite













Theorem. Given two countably infinite sequences of complex numbers ${a_{n}}_{n}$ and ${b_{n}}_{n}$ with $lim_{n to infty}|a_{n}| = infty$, it is always possible to find a entire function $F$ that satisfies $F(a_{n}) = b_{n}$ for all $n$.




First, I want to prove




Problem. If $a_1,dots,a_n$ and $b_1,dots,b_n$ are distinct complex numbers, I can construct a polynomial $p$ of degree $leq n-1$ such that $p(a_i) = b_i$ for all $i=1,dots,n$.




My approach.



$$c_{0} + c_{1}a_{1} + c_{2}a_{1}^{2} + cdots + c_{n-1}a_{1}^{n-1} = b_{1}$$
$$c_{0} + c_{1}a_{2} + c_{2}a_{2}^{2} + cdots + c_{n-1}a_{2}^{n-1} = b_{2}$$
$$vdots$$
$$c_{0} + c_{1}a_{n} + c_{2}a_{n}^{2} + cdots + c_{n-1}a_{n}^{n-1} = b_{n}$$
and so
$$left(begin{array}{ccccc}
1 & a_{1} & a_{1}^{2} & cdots & a_{1}^{n-1}\
1 & a_{2} & a_{2}^{2} & cdots & a_{2}^{n-1}\
vdots & vdots & vdots & ddots & vdots\
1 & a_{n} & a_{n}^{2} & cdots & a_{n}^{n-1}\
end{array}right)
left(begin{array}{c}
c_{0}\
c_{1}\
vdots\
c_{n-1}
end{array}right)
=
left(begin{array}{c}
b_{1}\
b_{2}\
vdots\
b_{n}
end{array}right)$$



What is the best method to solve this system? Or, Is there a better approach to this problem??










share|cite|improve this question


















  • 2




    This is called lagrange interpolation.
    – Robert Wolfe
    Nov 19 at 3:45










  • @RobertWolfe, thank you!
    – Lucas Corrêa
    Nov 19 at 3:49






  • 2




    Just like magic - if you the name of something, you gain power.
    – marty cohen
    Nov 19 at 4:20






  • 1




    For the main question see "An Interpoation Problem' in Rudin's RCA. [ Chapter on Zeros of Holomorphic Functions].
    – Kavi Rama Murthy
    Nov 19 at 5:28












  • @martycohen, absolutely! hahaha
    – Lucas Corrêa
    Nov 19 at 16:54













up vote
1
down vote

favorite









up vote
1
down vote

favorite












Theorem. Given two countably infinite sequences of complex numbers ${a_{n}}_{n}$ and ${b_{n}}_{n}$ with $lim_{n to infty}|a_{n}| = infty$, it is always possible to find a entire function $F$ that satisfies $F(a_{n}) = b_{n}$ for all $n$.




First, I want to prove




Problem. If $a_1,dots,a_n$ and $b_1,dots,b_n$ are distinct complex numbers, I can construct a polynomial $p$ of degree $leq n-1$ such that $p(a_i) = b_i$ for all $i=1,dots,n$.




My approach.



$$c_{0} + c_{1}a_{1} + c_{2}a_{1}^{2} + cdots + c_{n-1}a_{1}^{n-1} = b_{1}$$
$$c_{0} + c_{1}a_{2} + c_{2}a_{2}^{2} + cdots + c_{n-1}a_{2}^{n-1} = b_{2}$$
$$vdots$$
$$c_{0} + c_{1}a_{n} + c_{2}a_{n}^{2} + cdots + c_{n-1}a_{n}^{n-1} = b_{n}$$
and so
$$left(begin{array}{ccccc}
1 & a_{1} & a_{1}^{2} & cdots & a_{1}^{n-1}\
1 & a_{2} & a_{2}^{2} & cdots & a_{2}^{n-1}\
vdots & vdots & vdots & ddots & vdots\
1 & a_{n} & a_{n}^{2} & cdots & a_{n}^{n-1}\
end{array}right)
left(begin{array}{c}
c_{0}\
c_{1}\
vdots\
c_{n-1}
end{array}right)
=
left(begin{array}{c}
b_{1}\
b_{2}\
vdots\
b_{n}
end{array}right)$$



What is the best method to solve this system? Or, Is there a better approach to this problem??










share|cite|improve this question














Theorem. Given two countably infinite sequences of complex numbers ${a_{n}}_{n}$ and ${b_{n}}_{n}$ with $lim_{n to infty}|a_{n}| = infty$, it is always possible to find a entire function $F$ that satisfies $F(a_{n}) = b_{n}$ for all $n$.




First, I want to prove




Problem. If $a_1,dots,a_n$ and $b_1,dots,b_n$ are distinct complex numbers, I can construct a polynomial $p$ of degree $leq n-1$ such that $p(a_i) = b_i$ for all $i=1,dots,n$.




My approach.



$$c_{0} + c_{1}a_{1} + c_{2}a_{1}^{2} + cdots + c_{n-1}a_{1}^{n-1} = b_{1}$$
$$c_{0} + c_{1}a_{2} + c_{2}a_{2}^{2} + cdots + c_{n-1}a_{2}^{n-1} = b_{2}$$
$$vdots$$
$$c_{0} + c_{1}a_{n} + c_{2}a_{n}^{2} + cdots + c_{n-1}a_{n}^{n-1} = b_{n}$$
and so
$$left(begin{array}{ccccc}
1 & a_{1} & a_{1}^{2} & cdots & a_{1}^{n-1}\
1 & a_{2} & a_{2}^{2} & cdots & a_{2}^{n-1}\
vdots & vdots & vdots & ddots & vdots\
1 & a_{n} & a_{n}^{2} & cdots & a_{n}^{n-1}\
end{array}right)
left(begin{array}{c}
c_{0}\
c_{1}\
vdots\
c_{n-1}
end{array}right)
=
left(begin{array}{c}
b_{1}\
b_{2}\
vdots\
b_{n}
end{array}right)$$



What is the best method to solve this system? Or, Is there a better approach to this problem??







complex-analysis interpolation






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Nov 19 at 3:44









Lucas Corrêa

1,261321




1,261321








  • 2




    This is called lagrange interpolation.
    – Robert Wolfe
    Nov 19 at 3:45










  • @RobertWolfe, thank you!
    – Lucas Corrêa
    Nov 19 at 3:49






  • 2




    Just like magic - if you the name of something, you gain power.
    – marty cohen
    Nov 19 at 4:20






  • 1




    For the main question see "An Interpoation Problem' in Rudin's RCA. [ Chapter on Zeros of Holomorphic Functions].
    – Kavi Rama Murthy
    Nov 19 at 5:28












  • @martycohen, absolutely! hahaha
    – Lucas Corrêa
    Nov 19 at 16:54














  • 2




    This is called lagrange interpolation.
    – Robert Wolfe
    Nov 19 at 3:45










  • @RobertWolfe, thank you!
    – Lucas Corrêa
    Nov 19 at 3:49






  • 2




    Just like magic - if you the name of something, you gain power.
    – marty cohen
    Nov 19 at 4:20






  • 1




    For the main question see "An Interpoation Problem' in Rudin's RCA. [ Chapter on Zeros of Holomorphic Functions].
    – Kavi Rama Murthy
    Nov 19 at 5:28












  • @martycohen, absolutely! hahaha
    – Lucas Corrêa
    Nov 19 at 16:54








2




2




This is called lagrange interpolation.
– Robert Wolfe
Nov 19 at 3:45




This is called lagrange interpolation.
– Robert Wolfe
Nov 19 at 3:45












@RobertWolfe, thank you!
– Lucas Corrêa
Nov 19 at 3:49




@RobertWolfe, thank you!
– Lucas Corrêa
Nov 19 at 3:49




2




2




Just like magic - if you the name of something, you gain power.
– marty cohen
Nov 19 at 4:20




Just like magic - if you the name of something, you gain power.
– marty cohen
Nov 19 at 4:20




1




1




For the main question see "An Interpoation Problem' in Rudin's RCA. [ Chapter on Zeros of Holomorphic Functions].
– Kavi Rama Murthy
Nov 19 at 5:28






For the main question see "An Interpoation Problem' in Rudin's RCA. [ Chapter on Zeros of Holomorphic Functions].
– Kavi Rama Murthy
Nov 19 at 5:28














@martycohen, absolutely! hahaha
– Lucas Corrêa
Nov 19 at 16:54




@martycohen, absolutely! hahaha
– Lucas Corrêa
Nov 19 at 16:54















active

oldest

votes











Your Answer





StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3004496%2fconstruct-a-polynomial-p-of-degree-leq-n-1-such-that-pa-i-b-i%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown






























active

oldest

votes













active

oldest

votes









active

oldest

votes






active

oldest

votes
















draft saved

draft discarded




















































Thanks for contributing an answer to Mathematics Stack Exchange!


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


Use MathJax to format equations. MathJax reference.


To learn more, see our tips on writing great answers.





Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


Please pay close attention to the following guidance:


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


To learn more, see our tips on writing great answers.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3004496%2fconstruct-a-polynomial-p-of-degree-leq-n-1-such-that-pa-i-b-i%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







Popular posts from this blog

How to change which sound is reproduced for terminal bell?

Can I use Tabulator js library in my java Spring + Thymeleaf project?

Title Spacing in Bjornstrup Chapter, Removing Chapter Number From Contents