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include <math.h>
include "rvpackage.h"
include "rvflags.h"
include "rvplots.h"
# GET_FFT - Take the input real array and return the absolute value of it's
# DFT. The array rfft must be sized to at least to the power of two greater
# than npts.
procedure get_fft (rv, rinpt, npts, rfft, fnpts)
pointer rv #I RV struct pointer
real rinpt[ARB] #I Input real array
int npts #I No. pts in rinpt
real rfft[ARB] #O Output abs value of DFT
int fnpts #O No. pts in output array.
pointer sp, tp, cpr, cpi, fft
int i, last, ishift
real xtmp, cx_abs()
begin
fnpts = RV_FFTNPTS (rv) # Get FFT size
call smark (sp)
call salloc (tp, fnpts, TY_REAL) # Allocate temp vector
call salloc (cpr, fnpts, TY_REAL) # Allocate temp vector
call salloc (cpi, fnpts, TY_REAL)
call salloc (fft, 2*fnpts, TY_REAL)
call aclrr (Memr[tp], fnpts)
call aclrr (Memr[cpr], fnpts)
call aclrr (Memr[cpi], fnpts)
call amovr (rinpt, Memr[tp], npts)
# Do forward transform
ishift = 0
if (RV_WHERE(rv) == TOP) {
call prep_spec (rv, RV_OSAMPLE(rv), npts, fnpts, RV_NPTS(rv),
tp, cpr, ishift, YES)
} else {
call prep_spec (rv, RV_RSAMPLE(rv), npts, fnpts, RV_RNPTS(rv),
tp, cpr, ishift, YES)
}
call afftrr (Memr[cpr], Memr[cpi], Memr[cpr], Memr[cpi], fnpts)
if (RVP_WHEN(rv) == AFTER) {
if (RV_WHERE(rv) == TOP) {
if (RV_FILTER(rv) == OBJ_ONLY || RV_FILTER(rv) == BOTH) {
call cx_pak (Memr[cpr], Memr[cpi], Memr[fft], fnpts/2)
call rv_filter (rv, Memr[fft], fnpts/2)
call cx_unpak (Memr[fft], Memr[cpr], Memr[cpi], fnpts)
}
} else {
if (RV_FILTER(rv) == TEMP_ONLY || RV_FILTER(rv) == BOTH) {
call cx_pak (Memr[cpr], Memr[cpi], Memr[fft], fnpts/2)
call rv_filter (rv, Memr[fft], fnpts/2)
call cx_unpak (Memr[fft], Memr[cpr], Memr[cpi], fnpts)
}
}
}
# Get the absolute value of the transform
last = fnpts / 2 + 1
do i = 2, last {
xtmp = cx_abs (Memr[cpr+i-1], Memr[cpi+i-1])
if (RVP_LOG_SCALE(rv) == YES) {
if (xtmp != 0.0) # Divide by zero check in log
rfft[i-1] = log10 (xtmp)
else
rfft[i-1] = 0.0
} else
rfft[i-1] = xtmp
}
call sfree (sp)
end
# GET_PSPEC - Take the input real array and return the log of the power
# spectrum. The array pspec must be sized to at least to the power of two
# greater than npts.
procedure get_pspec (rv, rinpt, npts, pspec, fnpts)
pointer rv #I RV struct pointer
real rinpt[ARB] #I Input real array
int npts #I No. pts in rinpt
real pspec[ARB] #O Output abs value of DFT
int fnpts #O No. pts in output array.
pointer sp, tp, cpr, cpi, fft
int i, j, ishift
real xtmp
begin
fnpts = RV_FFTNPTS (rv) # Get FFT size
call smark (sp)
call salloc (tp, fnpts, TY_REAL) # Allocate temp vector
call salloc (cpr, fnpts, TY_REAL) # Allocate temp vector
call salloc (cpi, fnpts, TY_REAL) # Allocate temp vector
call salloc (fft, 2*fnpts, TY_REAL) # Allocate temp vector
call aclrr (Memr[tp], fnpts)
call aclrr (Memr[cpr], fnpts)
call aclrr (Memr[cpi], fnpts)
call amovr (rinpt, Memr[tp], npts)
# Do forward transform
ishift = 0
if (RV_WHERE(rv) == TOP) {
call prep_spec (rv, RV_OSAMPLE(rv), npts, fnpts, RV_NPTS(rv),
tp, cpr, ishift, YES)
} else {
call prep_spec (rv, RV_RSAMPLE(rv), npts, fnpts, RV_RNPTS(rv),
tp, cpr, ishift, YES)
}
call afftrr (Memr[cpr], Memr[cpi], Memr[cpr], Memr[cpi], fnpts)
if (RVP_WHEN(rv) == AFTER) {
if (RV_WHERE(rv) == TOP) {
if (RV_FILTER(rv) == OBJ_ONLY || RV_FILTER(rv) == BOTH) {
call cx_pak (Memr[cpr], Memr[cpi], Memr[fft], fnpts/2)
call rv_filter (rv, Memr[fft], fnpts/2)
call cx_unpak (Memr[fft], Memr[cpr], Memr[cpi], fnpts)
}
} else {
if (RV_FILTER(rv) == TEMP_ONLY || RV_FILTER(rv) == BOTH) {
call cx_pak (Memr[cpr], Memr[cpi], Memr[fft], fnpts/2)
call rv_filter (rv, Memr[fft], fnpts/2)
call cx_unpak (Memr[fft], Memr[cpr], Memr[cpi], fnpts)
}
}
}
# Get the power spectrum
j = fnpts / 2 + 1
do i = 2, j {
xtmp = (Memr[cpr+i-1]*Memr[cpr+i-1]) + (Memr[cpi+i-1]*Memr[cpi+i-1])
if (RVP_LOG_SCALE(rv) == YES) {
if (xtmp != 0.0)
pspec[i-1] = log10 (xtmp)
else
pspec[i-1] = 0.0
} else
pspec[i-1] = xtmp
}
call sfree (sp)
end
# FFT_COSBEL - Apply a cosine bell to the data.
procedure fft_cosbel (v, npts, code, percent)
real v[ARB] #U Data vector
int npts #I Number of data points
int code #I Direction code
# <0 for forward, >=0 for reverse
real percent #I percent of end to mask
int ndpercent, index, i
real f
begin
if (IS_INDEF(percent))
return
ndpercent = int (npts * percent) # Compute no. of endpoints
if (code < 0) { # Forward application of window
do i = 1,ndpercent {
f = (1.0 - cos(PI*real(i-1)/real(ndpercent))) / 2.0
index = npts - i + 1
v[i] = f * v[i]
v[index] = f * v[index]
}
} else if (code >= 0) { # Reverse application of window
do i = 1,ndpercent {
f = (1.0 - cos(PI*real(i-1)/real(ndpercent))) / 2.0
if (abs(f) < 1.0e-3)
f = 1.0e-3
index = npts - i + 1
v[i] = v[i] / f
v[index] = v[index] / f
}
}
end
# FFT_FIXWRAP - Fix the wrap around ordering that results from the Numerical
# Recipes FFT routines. Re-ordering is done such that points 1 to N/2 are
# switched in the array with points N/2+1 to N. Re-ordering is done in-place.
procedure fft_fixwrap (v, npts)
real v[ARB] #U Data array in wrap around order
int npts #I length of data array
real temp
int i
begin
do i = 1, npts/2 {
temp = v[i]
v[i] = v[i+npts/2]
v[i+npts/2] = temp
}
end
# FFT_POW2 - Find the power of two that is greater than N.
# Returns INDEFI if a power can't be found less than 2^15.
int procedure fft_pow2 (N)
int N #I Number of data points
int i, nn
begin
nn = 0
do i = 1, 31 {
nn = 2 ** i
if (nn >= N) # return 2**i > N
return (nn)
}
return (INDEFI)
end
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