TypeError: Cannot cast ufunc multiply output from dtype('float64') to dtype('int16') with casting rule 'same_kind'

import numpy

A = numpy.array([1, 2, 3, 4], dtype=numpy.int16)
B = numpy.array([0.5, 2.1, 3, 4], dtype=numpy.float64)

A *= B

Solution:

Replace A *= B with A = A * B or numpy.multiply(A, B, out=A, casting='unsafe')