Matrix Multiplication


A

amitsoni.1984

Hi,

Is there any direct function for matrix multiplication in Python or
any of its packages? or do we have to multiply element by element?

Thank you,
Amit
 
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S

sturlamolden

Hi,

Is there any direct function for matrix multiplication in Python or
any of its packages? or do we have to multiply element by element?

Use numpy: www.scipy.org

NumPy has a matrix type that overloads the * operator.
 
J

Jeremy Sanders

sturlamolden said:
Use numpy: www.scipy.org

NumPy has a matrix type that overloads the * operator.

Just a tiny followup, which may be important unless you carefully read the
documentation. The "*" operator doesn't do matrix multiplication for normal
numpy arrays - you do need to use its special matrix type to get this. You
can use the dot function to get matrix multiplication with its normal
arrays.

Jeremy
 
S

sturlamolden

Just a tiny followup, which may be important unless you carefully read the
documentation. The "*" operator doesn't do matrix multiplication for normal
numpy arrays


That's what I wrote: "NumPy has a matrix type." It is called called
numpy.matrix.

I did not suggest using the array type numpy.array.

Reading carefully is indeed important...
 
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J

Jeremy Sanders

sturlamolden said:
That's what I wrote: "NumPy has a matrix type." It is called called
numpy.matrix.

I did not suggest using the array type numpy.array.

Reading carefully is indeed important...

I know what you wrote and you are strictly correct. I was just clarifying it
for a reader who may not have instantly realised that there were multiple
array types in numpy (I didn't for a while), and could have wasted many
hours and been discouraged.

Explaining clearly is indeed important.
 

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