Function shallow_water::stafft::forfft

pub fn forfft(
    m: usize, 
    n: usize, 
    xs: ArrayViewMut2<'_, f64>, 
    trig: &[f64], 
    factors: &[usize; 5]
)

Main physical to spectral (forward) FFT routine. Performs m transforms of length n in the array x which is dimensioned x(m,n). The arrays trig and factors are filled by the init routine and should be kept from call to call. Backend consists of mixed-radix routines, with 'decimation in time'. Transform is stored in Hermitian form.