Ask Your Question

Revision history [back]

click to hide/show revision 1
initial version

Element-wise product of matrices

I am trying to calculate Hadamard product of two matrices.

def elementwise(M, N):
    assert(M.parent() == N.parent())
    nc, nr = M.ncols(), M.nrows()
    A = copy(M.parent().zero_element())
    for r in xrange(nr):
        for c in xrange(nc):
            A[r,c] = M[r,c] * N[r,c]
    return A

ring = PolynomialRing(QQ, 1, 'x') T = Matrix(ring, [ [1,-x,-x,0], [-x,1,0,-x], [0,-x,1,0], [-x,0,0,1]])

R = Matrix(QQ, [ [1,1,0,1], [1,1,1,0], [1,0,0,1], [0,1,1,0]])

B = ~T elementwise(B,R)

I get a following mistake

Error in lines 21-21
Traceback (most recent call last):
  File "/projects/sage/sage-7.5/local/lib/python2.7/site-packages/smc_sagews/", line 982, in execute
    exec compile(block+'\n', '', 'single') in namespace, locals
  File "", line 1, in <module>
  File "", line 2, in elementwise

Although elementwise(B,R) does not work, the program calculates elementwise(B,B) and elementwise(R,R) without any mistakes. Probably that's because matrices B and R have different types (B is a dense matrix over general ring and R is a rational dense matrix). What should I do?