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NumPy is a python library for working with arrays.

Memory Usage

To optimize memory usage, try to use views instead of actual arrays where possible.
Indexing into an array will return a view. See numpy indexing for details.
Fancy indexing, using a list of indices, will not return a view.

The following functions also return views

Most function calls will return a new array. E.g. a+b will return a new array with the broadcasted size which requires memory allocation.
To output to an existing array c, you can use np.add(a, b, out=c).
If you need to perform an operation over multiple arrays, you can use np.ufunc.reduce. E.g. np.logical_and.reduce((a, b, c)).

Batched Multiplication

If you need batched matrix multiplication, use np.tensordot and transpose the result.