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fftreal

void fftreal( int * x, int N, int * blockexp );

Description

Computes the N-point, positive-frequency complex spectrum of the 2N-point real sequence in array x. The 2N-point real sequence in array x is replaced with its N-point positive-frequency complex spectrum. The value of blockexp is increased by 1 each time array x has to be scaled, to avoid arithmetic overflow.

The imaginary part of the X[0] term (stored in x[1]) is set to the real part of the fmax term.

The 2N-point real sequence is stored in natural order. The zeroth element of the sequence is stored in x[0], the first element in x[1], and the kth element in x[k].

N must be a power of 2 and lie between 4 and 1024. An invalid N causes a RANGE exception.

Parameters

x

Pointer to 2N-point sequence of real fractions.

N

Number of complex elements in output spectrum

blockexp

Pointer to integer block exponent.

Library

FFT.LIB

See also

fftcplx, fftcplxinv, fftrealinv, hanncplx, hannreal, powerspectrum