want to multiply two matrices each time in a particular position according to randperm matrix position

hi all, i want to multiply 2 50 x 50 matrix, according to the position of reandperm matrix. i.e first i ll generate randperm matrix, it consists of 50 elements. Now according to the elements in randperm ie if the first element is 20,i want to multiply 20 th position element in the both matrix. like this i have to multiply all 50 positions and have to sum it. how to do it in matlab. If anyone know, Pls suggest me too.

[Cedric]

What are you calling "20th element" of 50x50 matrices? Is it a linear index(?), an index related to diagonals(?), anything else?

Answer 1

[Matt J]

 rp=randperm(50);

 result = dot( Matrix1(rp), Matrix2(rp));

Answer 2

[Matt J]

 rp=randperm(50);

 result = Matrix1(rp,:)*Matrix2(:,rp);

or

 result = Matrix1(:,rp)*Matrix2(rp,:);