Esempio n. 1
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def kron(a,b):
    """kronecker product of a and b

    Kronecker product of two matrices is block matrix
    [[ a[ 0 ,0]*b, a[ 0 ,1]*b, ... , a[ 0 ,n-1]*b  ],
     [ ...                                   ...   ],
     [ a[m-1,0]*b, a[m-1,1]*b, ... , a[m-1,n-1]*b  ]]
    """
    if not a.iscontiguous():
        a = reshape(a, a.shape)
    if not b.iscontiguous():
        b = reshape(b, b.shape)
    o = outerproduct(a,b)
    o.shape = a.shape + b.shape
    return concatenate(concatenate(o, axis=1), axis=1)
Esempio n. 2
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def ifftshift(x,axes=None):
    """ ifftshift(x,axes=None) - > y

    Inverse of fftshift.
    """
    tmp = asarray(x)
    ndim = len(tmp.shape)
    if axes is None:
        axes = range(ndim)
    y = tmp
    for k in axes:
        n = tmp.shape[k]
        p2 = n-(n+1)/2
        mylist = concatenate((arange(p2,n),arange(p2)))
        y = take(y,mylist,k)
    return y
Esempio n. 3
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def fftshift(x,axes=None):
    """ fftshift(x, axes=None) -> y

    Shift zero-frequency component to center of spectrum.

    This function swaps half-spaces for all axes listed (defaults to all).

    Notes:
      If len(x) is even then the Nyquist component is y[0].
    """
    tmp = asarray(x)
    ndim = len(tmp.shape)
    if axes is None:
        axes = range(ndim)
    y = tmp
    for k in axes:
        n = tmp.shape[k]
        p2 = (n+1)/2
        mylist = concatenate((arange(p2,n),arange(p2)))
        y = take(y,mylist,k)
    return y