In-Place Functions for 1D Multiple-Signal Complex FFT

Overview

The functions in this group use the following operation for a complex-to-complex transform:

N = 1 << Log2N;

scale = 0 < Direction ? 1 : 1./N;

// Repeat M times:
for (m = 0; m < M; ++m)
{

    // Define a complex vector, h:
    for (j = 0; j < N; ++j)
        h[j] = C->realp[m*IM + j*IC] + i * C->imagp[m*IM + j*IC];

    // Perform Discrete Fourier Transform.
    for (k = 0; k < N; ++k)
        H[k] = scale * sum(h[j]
            * e**(-Direction*2*pi*i*j*k/N), 0 <= j < N);

    // Store result.
    for (k = 0; k < N; ++k)
    {
        C->realp[m*IM + k*IC] = Re(H[k]);
        C->imagp[m*IM + k*IC] = Im(H[k]);
    }

}

The temporary buffer versions perform the same operation but use a temporary buffer for improved performance.

See Also

Functions for 1D Multiple-Signal Complex FFT

• Out-of-Place Functions for 1D Multiple-Signal Complex FFT