Size

Why I cannot use a matrix with dimension 256x256 ?

On what computer?
.

ghassankhaleel:
Why I cannot use a matrix with dimension 256x256 ?

And how much memory would that matrix require?

Regards,
Ray L.

ghassankhaleel:
Why I cannot use a matrix with dimension 256x256 ?

256x256 of what? Byte? Int? Float? Long?

So you want at least 65536 bytes? Have you checked the spec for your processor? How much RAM does it have?