MATLAB Answers

How to use an anonymous function in a ''for''?

1 view (last 30 days)
Hi everyone!!
I'm trying to write a general solution for a differential equation using a moment method (Galerkin, with polynomials as base functions). When I try to write the general solution por N polynomials, the anonymous function that I'm using, it doesnt update with every loop. I write my code:
N = 10; %number of elements;
l = zeros([N,N]);
g = zeros(N,1);
A = zeros (N,1);
f = @(x) 0;
for i=1:N
for k = 1:N;
l(i,k) = i*k/(i+k+1);
g(k,1) = (k*(8+3*k))/(2*(2+k)*(4+k));
A = linsolve(l,g);
f = @(x) f(x) + A(i,1)*(x - x.^(i+1));
end
end
Thanks!!
  3 Comments
Steven Lord
Steven Lord on 15 Oct 2020
Use the sum function and element-wise operations inside the anonymous function.

Sign in to comment.

Accepted Answer

Asad (Mehrzad)  Khoddam
Asad (Mehrzad) Khoddam on 15 Oct 2020
if you don't need to use it inside loop. you can define f(x) after for loop:
N = 10; %number of elements;
l = zeros([N,N]);
g = zeros(N,1);
A = zeros (N,1);
for i=1:N
for k = 1:N;
l(i,k) = i*k/(i+k+1);
g(k,1) = (k*(8+3*k))/(2*(2+k)*(4+k));
A = linsolve(l,g);
f = @(x) f(x) + A(i,1)*(x - x.^(i+1));
end
end
f = @(x) sum(A'.*(x-x.^(2:N+1)));
  1 Comment
Migue Balma
Migue Balma on 15 Oct 2020
Thank you for your answer!! But when I insert and array of values, for example, x1 = linspace (0,1). It gives me an error, that can't evaluate f(x1) to represent it in a plot, I don't know why.
Edit: I solve it using another ''for'' to evaluate the function:
x1 = linspace(0,1)
f1 = zeros(1,length(x1));
for j = 1: length (x1);
f1(j) = f(x1(j));
end
Thank you so much!! You solved my question!

Sign in to comment.

More Answers (0)

Products


Release

R2017b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by