Constructor function for class 'swdft2d'
new_swdft2d(a, x, n0, n1, type)
4D complex-valued array of 2D SWDFT coefficients
2D real or complex valued signal
window size in row direction
window size in column direction
algorithm to implement. defaults to "fftw", other option 'fft' for R's base FFT function. R's base fft function is used if
S3 object w/ the same elements as arguments to this constructor function