Python High Performance - Second Edition

Generalized universal functions

One of the main limitations of universal functions is that they must be defined on scalar values. A generalized universal function, abbreviated gufunc, is an extension of universal functions to procedures that take arrays.

A classic example is the matrix multiplication. In NumPy, matrix multiplication can be applied using the np.matmul function, which takes two 2D arrays and returns another 2D array. An example usage of np.matmul is as follows:

    a = np.random.rand(3, 3)    b = np.random.rand(3, 3)    c = np.matmul(a, b)    c.shape    # Result:    # (3, 3)

As we saw in the previous subsection, a ufunc broadcasts the operation over arrays of scalars, its natural generalization will be to broadcast over an array of arrays