## create matrix with integral

Asked by Mohammed Hachemi

### Mohammed Hachemi (view profile)

on 15 Sep 2019
Latest activity Answered by Mohammed Hachemi

### Mohammed Hachemi (view profile)

on 15 Sep 2019
Accepted Answer by Walter Roberson

### Walter Roberson (view profile)

Hello
I need your help , I am beginner in matlab and want to use matlab to calculate integral and create matrix with variable n and m.
x = [-1,1]
∫ (f(x,n)*f(x,m)dx
I want to creat matrix
f(x,1)*(f(x,1) f(x,1)*(f(x,2) .....
f(x,2)*(f(x,1) f(x,1)*(f(x,1)
.
.
I try this code but I need your help to create one
P = 5; exemple
fun(1) =@(x)(1-x)/2;
fun(2) =@(x)(1+x)/2;
fun(n) =@(x) sin(pi/2*(n-1).*(1+x)); if n >= 2;
for m = 1:P;
for n = 1:P;
L[n,m]=integral((fun(m).*fun(n)),-1,1,-1,1);
end
end

### Walter Roberson (view profile)

Answer by Walter Roberson

### Walter Roberson (view profile)

on 15 Sep 2019

P = 5;
for m = 1:P;
for n = 1:P;
L(n,m) = integral( @(x) fun(x,n).*fun(x,n)), -1, 1);
end
end
function y = fun(x, n)
%warning: x will be a vector or array!
if n == 1
y = (1-x)/2;
elseif n == 2
y = (1+x)/2;
else
y = sin(pi/2*(n-1).*(1+x));
end

### Mohammed Hachemi (view profile)

Answer by Mohammed Hachemi

### Mohammed Hachemi (view profile)

on 15 Sep 2019

Thank you for your answer but it doesn't work.