Adding 2 matrix and Multiplying 2 matrix in python by using scipy/numpy

Question

I am trying to use scipy and numpy to perform matrix addition and multiplication.

I have 2 matrix "a" and "b". my goal is to add "a" and "b" together and store the result into a matrix "c"

Also I want to multiply "a" and "b" and store into a matrix "d".

Are there any function perform like that in Scipy/Numpy?

Thanks a lot.

numpy's matrix type does matrix multiplication, while the array type does pointwise multiplication, which do you want? — sverre
– sverre, Commented May 23, 2011 at 2:57
Is matrix multiplication like "dot product" when pointwise multiplcation is like every point multiply corresponding point? — Hold_My_Anger
– Hold_My_Anger, Commented May 23, 2011 at 3:03
Yes. Check it out in a console and see for yourself. If you could give me some example data and what result you expect I could tell you which operation you want. — sverre
– sverre, Commented May 23, 2011 at 3:04
I am doing image processing in python, a method called Pyramid Based Data Fusion Scheme. I have one question: Is there only one way to do addition of two matrix? — Hold_My_Anger
– Hold_My_Anger, Commented May 23, 2011 at 3:10
Numpy for Matlab Users (scipy.org/NumPy_for_Matlab_Users) has a nice summary of numpy ndarray and matrix operations. element-wise operations, broadcasting, matrix operations, etc. — matt
– matt, Commented May 23, 2011 at 5:03

sverre · Accepted Answer · 2011-05-23 03:09:51Z

14

Matrix multiplication:

a = numpy.matrix(a)
b = numpy.matrix(b)
c = a+b
d = a*b

Array multiplication (map operator.mul):

a = numpy.array(a)
b = numpy.array(b)
c = a+b
d = a*b

answered May 23, 2011 at 2:55

sverre

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