spyrit.misc.walsh_hadamard.walsh_S

spyrit.misc.walsh_hadamard.walsh_S(x, S=None)[source]

Return the Walsh S-transform of the signal x

Args:

x (np.ndarray): signals of shape (*,n), where n+1 must be a power of two.

H (np.ndarray, optional): S-matrix of order n.

Returns:

np.ndarray: S-transformed signal of shape (*,n).

Examples:

Example 1: Walsh-ordered S-transform of a signal of length 7

>>> import spyrit.misc.walsh_hadamard as wh
>>> x = np.array([1, 3, 0, -1, 7, 5, 1])
>>> s = wh.walsh_S(x)
>>> print(s)
[12.  9.  9. 16.  4.  5.  9.]

Example 2: Walsh-ordered S-transform of two signals of length 7

>>> import spyrit.misc.walsh_hadamard as wh
>>> x = np.array([[1, 3, 0, -1, 7, 5, 1],[2, 1, -1, 0, 4, 5, 3]])
>>> s = wh.walsh_S(x)
>>> print(s)
[[12.  9.  9. 16.  4.  5.  9.]
 [12.  4.  8. 12.  6.  6.  8.]]