MATLAB: Replacing components of a matrix

MATLABmatricesmatrixmatrix manipulation

how to generate a matrix that replaces all components of a previous matrix lying between 2.9 and 3.2, by -1?

%your matrix is M
isBetween = (M >= 2.9) & (M <= 3.2);
M(isBetween) = -1

Is this what you're asking for?

A(A>3.1)

- Rob

You can use blkdiag for this:

>> A = [1 2 3; 2 3 4];
>> B = num2cell(A,2);
>> blkdiag(B{:})
ans =
   1     2     3     0     0     0
   0     0     0     2     3     4

This is not an identity matrix though.