pynufft_gpu.py 文件源码

def nufft_T(N, J, K, alpha, beta):
    '''
     equation (29) and (26)Fessler's paper
     create the overlapping matrix CSSC (diagonal dominent matrix)
     of J points
     and then find out the pseudo-inverse of CSSC '''

#     import scipy.linalg
    L = numpy.size(alpha) - 1
#     print('L = ', L, 'J = ',J, 'a b', alpha,beta )
    cssc = numpy.zeros((J, J))
    [j1, j2] = numpy.mgrid[1:J + 1, 1:J + 1]
    overlapping_mat = j2 - j1

    for l1 in range(-L, L + 1):
        for l2 in range(-L, L + 1):
            alf1 = alpha[abs(l1)]
#             if l1 < 0: alf1 = numpy.conj(alf1)
            alf2 = alpha[abs(l2)]
#             if l2 < 0: alf2 = numpy.conj(alf2)
            tmp = overlapping_mat + beta * (l1 - l2)

            tmp = dirichlet(1.0 * tmp / (1.0 * K / N))
            cssc = cssc + alf1 * numpy.conj(alf2) * tmp
    return mat_inv(cssc)