I would like to use a matrix with complex entries to construct a new matrix, but it gives me the warning

"ComplexWarning: Casting complex values to real discards the imaginary part".

As a result, the new matrix's entries are all real numbers. How to make all the entries keep their imaginary part?

This is the image containing my original code

I know where I make this warning happen.

I need to add dtype = "complex_", when I construct a new empty matrix.

For example,

mat__ = np.zeros((k*nboxes,k*nboxes),dtype = 'complex_')

If we just write

mat__ = np.zeros((k*nboxes,k*nboxes))

and do some manipulations on that like using a complex matrix to forming a new matrix, then the new matrix will discard the imaginary part.