I have ( An ) matrix, I need generalised algorithm to calculate An-1 = An *B. Here An-1, An, and B are matrices.

For example, I have A3 matrix, such that i want to calculate matrices of A2, A1. A2= A3*B, A1=A2*B, here B is a matrix..... For matrix (An), I need generalised algorithm to calculate matrices An-1, An-2....A3, A2, A1, An-1=An*B, An-2= An-1*B .........A2=A1*B respectively.

[Stephen23]

"I need generalised algorithm to calculate matrices An-1, An-2....A3, A2, A1, An-1=An*B, An-2= An-1*B .........A2=A1*B respectively"

Do NOT do this. Magically accessing variable names is one way that beginners force themselves into writing slow, complex, buggy code that is hard to debug. Read this to know why:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Learn to use arrays and indexing. Your problem will be much simpler and more efficient with one array (e.g. cell, ND numeric) and indexing.

Answer 1

[John D'Errico]

You have A3, and you want to compute A2 and A1?

A2 = A3*B;
A1 = A2*B;

You want a general "algorithm"?

DON'T DO IT. Don't create numbered variables. That is just a bad idea. I know, you want to. DON'T DO IT.

Instead, learn to use multidimensional arrays. Or, learn to use cell arrays.

B = rand(3,3);
An = rand(3,3);

n = 10;

A = zeros(3,3,10);
A(:,:,n) = An;
for i = n-1:-1:1
  A(:,:,i) = A(:,:,i+1)*B;
end

[sukumar nagineni]

Thanks a lot