How can I create a function that returns a function?

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Vitor Pessoa
Vitor Pessoa 2016-8-14
回答： Walter Roberson 2016-8-14
I'm tryng to create a function that returns to me the interpolation polynom of newton. This is the code:
function Y=newton(x,y)
syms X;
n=length(x);
b=zeros(n,n);
b(:,1)=y(:);
%finite difference matrix
for j=2:n
for i=1:n-j+1
b(i,j)= (b(i+1,j-1)-b(i,j-1))/(x(i+j-1)-x(i));
end
end
%interpolation polynom
yint=b(1,1);
xt=1;
for j=1:n-1
xt=xt*(X-x(j));
yint=yint+b(1,j+1)*xt;
end
Y=yint
It's already working, but I want the output to be a function, so I can calculate it's value in any point, make graphics, etc.
  2 个评论
Vitor Pessoa
Vitor Pessoa 2016-8-14
编辑：Geoff Hayes 2016-8-14
function Y=newton(x,y)
syms X;
n=length(x);
b=zeros(n,n);
b(:,1)=y(:);
%finite difference matrix
for j=2:n
for i=1:n-j+1
b(i,j)= (b(i+1,j-1)-b(i,j-1))/(x(i+j-1)-x(i));
end
end
%interpolation polynom
yint=b(1,1);
xt=1;
for j=1:n-1
xt=xt*(X-x(j));
yint=yint+b(1,j+1)*xt;
end
Y=yint
Sorry, it was supposed to come out like this.
Geoff Hayes
Geoff Hayes 2016-8-14
Vitor - to properly format your code, highlight that text which is code and press the {}Code button.

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回答（1 个）

Walter Roberson
Walter Roberson 2016-8-14
Functions cannot return functions. Functions can return function handles, and functions can return symbolic expressions, and functions can return symbolic functions. The Y that you compute is already a symbolic expression; if you want to turn it into a function handle, use matlabFunction

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