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#include "pv.h"
void leanconvert( float *S, float *C, int N2 )
{
register int i;
float a = S[0]; // real value at f=0
float b = S[1]; // real value at f=Nyquist
C[0] = fabs(a);
C[1] = 0;
S += 2,C += 2;
for ( i = 1; i < N2; i++,S += 2,C += 2 ) {
C[0] = hypot( S[0], S[1] );
C[1] = -atan2( S[1], S[0] );
}
C[0] = fabs(b);
C[1] = 0;
}
/* unconvert essentially undoes what convert does, i.e., it
turns N2+1 PAIRS of amplitude and frequency values in
C into N2 PAIR of complex spectrum data (in rfft format)
in output array S; sampling rate R and interpolation factor
I are used to recompute phase values from frequencies */
void leanunconvert( float *C, float *S, int N2 )
{
register int i;
S[0] = fabs(C[0]);
S[1] = fabs(C[N2*2]);
S += 2,C += 2;
for (i = 1; i < N2; i++,S += 2,C += 2 ) {
S[0] = C[0] * cos( C[1] );
S[1] = -C[0] * sin( C[1] );
}
}
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