inverse of a subset of a matrix

Hi everyone,

I have a matrix that has an n by p dimension and I would like to grab all the 3x3 submatrices and inverse them. also by the end of the operation, I would like to put them back as n by p matrix.

As an exemple 3x28 matrix.

Hope to hear from you.

Answer 1

[Sahithi Kanumarlapudi]

As 28 is not a multiple of 3 I am assuming that you are looking to invert 9 3x3 sub matrices I.e., till row 27

The following code can be used to obtain your required functionality where A is the matrix to be inverted

matLength = length(A); 
r = rem(matLength,3); 
mLength = matLength-r; 
for i =1:3:mLength 
    x = A([i:i+2],:); 
    a = inv(x); 
    A([i:i+2],:) = a; 
end 

[zakaria azdad]

Sorry, for late reply.

Your guess was correct.

I have found another way to do it. I just converted each cell to matrix , invert it and put it back to a new cell with I just converted But it a bit longer than your method :)

Thanks a lot