Integration of a joint pdf with for loop?

Hi, everyone

I want to Integration of a joint pdf which is square matrix using for loop, But i have error

"Index in position 2 is invalid. Array indices must be positive integers or logical values"

clc;
clear;
close all;
%%
x = linspace(0,1,100);
y = linspace(0,1,100);

[x y] = meshgrid(x,y);

fun = (6/5).*(x + y.^2);

dx = 1/length(x);

f = zeros(size(x));
fz = zeros(size(x));

for k = 1:2*length(x)% w = u + v;
    for i = 1:length(x) %u
         for j = 1:length(x) %v
             
             if 0<=k-i && k-i<=100
                 
          f(i,j) = fun(i,k-i);
          
             end
         
         end
    fz(k,:) = fz + trapz(f(:,i))*dx;
   end
      
end       

Answer 1

[Alan Stevens]

When k = 1and i = 1 then k-i = 0, therefore the second index in fun(i,k-i) is 0, but indices must be positive integers in Matlab.

[Mk]

Hi, Alan,

thanks for your answer.

i change k=2:2*length(x) but still I Have that error.

What can i do to solve this problem?

[Alan Stevens]

There are lots of other values for which k=i, so k-i = 0 (e.g when k = 2, you also get to i = 2). You need to rethink the logic!