Fast fourier transform for transient data analysis
This commit is contained in:
h_vogt
parent
153a89afcd
commit
655d8aea02
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@ -22,3 +22,6 @@ ylwrap
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*.tar.gz
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visualc
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autogen-new.log
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make.log
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@ -1,3 +1,6 @@
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2008-05-24 Holger Vogt
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* src/frontend/com_fft.c: Fast fourier transform added for transient data analysis.
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2008-05-18 Dietmar Warning
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* Small changes to compile under Sun Studio 11 for Solaris - may be useful in other
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configurations too
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@ -55,6 +55,8 @@ libfte_a_SOURCES = \
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com_shell.h \
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com_shift.c \
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com_shift.h \
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com_fft.c \
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com_fft.h \
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com_state.c \
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com_state.h \
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com_strcmp.c \
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@ -0,0 +1,328 @@
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/**********
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Copyright 2008 Holger Vogt. All rights reserved.
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Author: 2008 Holger Vogt
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**********/
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/*
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* Code to do fast fourier transform on data.
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*/
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#include "ngspice.h"
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#include "ftedefs.h"
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#include "dvec.h"
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#include "sim.h"
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#include "com_fft.h"
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#include "variable.h"
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#include "missing_math.h"
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void
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com_fft(wordlist *wl)
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{
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complex **fdvec;
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double **tdvec;
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double *freq, *win, *time;
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double delta_t, span;
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int fpts, i, j, tlen, ngood;
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struct dvec *f, *vlist, *lv, *vec;
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struct pnode *names, *first_name;
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float *reald, *imagd;
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int size, sign, isreal;
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float scaling;
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if (!plot_cur || !plot_cur->pl_scale) {
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fprintf(cp_err, "Error: no vectors loaded.\n");
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return;
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}
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if (!isreal(plot_cur->pl_scale) ||
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((plot_cur->pl_scale)->v_type != SV_TIME)) {
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fprintf(cp_err, "Error: fft needs real time scale\n");
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return;
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}
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tlen = (plot_cur->pl_scale)->v_length;
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time = (plot_cur->pl_scale)->v_realdata;
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span = time[tlen-1] - time[0];
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delta_t = span/(tlen - 1);
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// size of input vector is power of two and larger than spice vector
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size = 1;
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while (size < tlen)
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size *= 2;
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// output vector has length of size/2
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fpts = size/2;
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// window function
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win = (double *) tmalloc(tlen * sizeof (double));
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{
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char window[BSIZE_SP];
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double maxt = time[tlen-1];
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if (!cp_getvar("specwindow", VT_STRING, window))
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strcpy(window,"blackman");
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if (eq(window, "none"))
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for(i=0; i<tlen; i++) {
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win[i] = 1;
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}
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else if (eq(window, "rectangular"))
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for(i=0; i<tlen; i++) {
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if (maxt-time[i] > span) {
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win[i] = 0;
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} else {
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win[i] = 1;
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}
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}
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else if (eq(window, "hanning") || eq(window, "cosine"))
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for(i=0; i<tlen; i++) {
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if (maxt-time[i] > span) {
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win[i] = 0;
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} else {
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win[i] = 1 - cos(2*M_PI*(time[i]-maxt)/span);
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}
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}
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else if (eq(window, "hamming"))
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for(i=0; i<tlen; i++) {
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if (maxt-time[i] > span) {
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win[i] = 0;
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} else {
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win[i] = 1 - 0.92/1.08*cos(2*M_PI*(time[i]-maxt)/span);
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}
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}
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else if (eq(window, "triangle") || eq(window, "bartlet"))
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for(i=0; i<tlen; i++) {
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if (maxt-time[i] > span) {
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win[i] = 0;
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} else {
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win[i] = 2 - fabs(2+4*(time[i]-maxt)/span);
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}
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}
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else if (eq(window, "blackman")) {
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int order;
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if (!cp_getvar("specwindoworder", VT_NUM, &order)) order = 2;
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if (order < 2) order = 2; /* only order 2 supported here */
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for(i=0; i<tlen; i++) {
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if (maxt-time[i] > span) {
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win[i] = 0;
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} else {
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win[i] = 1;
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win[i] -= 0.50/0.42*cos(2*M_PI*(time[i]-maxt)/span);
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win[i] += 0.08/0.42*cos(4*M_PI*(time[i]-maxt)/span);
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}
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}
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} else if (eq(window, "gaussian")) {
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int order;
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double scale;
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extern double erfc();
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if (!cp_getvar("specwindoworder", VT_NUM, &order)) order = 2;
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if (order < 2) order = 2;
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scale = pow(2*M_PI/order,0.5)*(0.5-erfc(pow(order,0.5)));
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for(i=0; i<tlen; i++) {
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if (maxt-time[i] > span) {
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win[i] = 0;
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} else {
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win[i] = exp(-0.5*order*(1-2*(maxt-time[i])/span)
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*(1-2*(maxt-time[i])/span))/scale;
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}
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}
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} else {
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fprintf(cp_err, "Warning: unknown window type %s\n", window);
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tfree(win);
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return;
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}
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}
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names = ft_getpnames(wl, TRUE);
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first_name = names;
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vlist = NULL;
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ngood = 0;
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while (names) {
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vec = ft_evaluate(names);
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names = names->pn_next;
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while (vec) {
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if (vec->v_length != tlen) {
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fprintf(cp_err, "Error: lengths of %s vectors don't match: %d, %d\n",
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vec->v_name, vec->v_length, tlen);
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vec = vec->v_link2;
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continue;
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}
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if (!isreal(vec)) {
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fprintf(cp_err, "Error: %s isn't real!\n",
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vec->v_name);
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vec = vec->v_link2;
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continue;
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}
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if (vec->v_type == SV_TIME) {
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vec = vec->v_link2;
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continue;
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}
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if (!vlist)
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vlist = vec;
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else
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lv->v_link2 = vec;
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lv = vec;
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vec = vec->v_link2;
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ngood++;
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}
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}
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free_pnode(first_name);
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if (!ngood) {
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return;
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}
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plot_cur = plot_alloc("spectrum");
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plot_cur->pl_next = plot_list;
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plot_list = plot_cur;
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plot_cur->pl_title = copy((plot_cur->pl_next)->pl_title);
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plot_cur->pl_name = copy("Spectrum");
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plot_cur->pl_date = copy(datestring( ));
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freq = (double *) tmalloc(fpts * sizeof(double));
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f = alloc(struct dvec);
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ZERO(f, struct dvec);
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f->v_name = copy("frequency");
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f->v_type = SV_FREQUENCY;
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f->v_flags = (VF_REAL | VF_PERMANENT | VF_PRINT);
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f->v_length = fpts;
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f->v_realdata = freq;
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vec_new(f);
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for (i = 0; i<fpts; i++) freq[i] = i*1./span*tlen/size;
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tdvec = (double **) tmalloc(ngood * sizeof(double *));
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fdvec = (complex **) tmalloc(ngood * sizeof(complex *));
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for (i = 0, vec = vlist; i<ngood; i++) {
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tdvec[i] = vec->v_realdata; /* real input data */
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fdvec[i] = (complex *) tmalloc(fpts * sizeof(complex)); /* complex output data */
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f = alloc(struct dvec);
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ZERO(f, struct dvec);
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f->v_name = vec_basename(vec);
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f->v_type = SV_NOTYPE; //vec->v_type;
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f->v_flags = (VF_COMPLEX | VF_PERMANENT);
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f->v_length = fpts;
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f->v_compdata = fdvec[i];
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vec_new(f);
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vec = vec->v_link2;
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}
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sign = 1;
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isreal = 1;
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reald = (float*)malloc(size*sizeof(float));
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imagd = (float*)malloc(size*sizeof(float));
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printf("CPU: Delta Freq %f Hz, input length %d, output length %d\n", 1./span*tlen/size, size, fpts);
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for (i = 0; i<ngood; i++) {
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for (j = 0; j < tlen; j++){
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reald[j] = tdvec[i][j]*win[j];
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imagd[j] = 0;
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}
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for (j = tlen; j < size; j++){
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reald[j] = 0;
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imagd[j] = 0;
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}
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fftext(reald, imagd, size, sign);
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scaling = 0.3;
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for (j=0;j<fpts;j++){
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fdvec[i][j].cx_real = reald[j]/scaling;
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fdvec[i][j].cx_imag = imagd[j]/scaling;
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}
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}
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free(reald);
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free(imagd);
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tfree(tdvec);
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tfree(fdvec);
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}
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static void fftext(float* x, float* y, long int n, int dir)
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{
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/*
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http://local.wasp.uwa.edu.au/~pbourke/other/dft/
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download 22.05.08
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*/
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/*
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This computes an in-place complex-to-complex FFT
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x and y are the real and imaginary arrays
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n is the number of points, has to be to the power of 2
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dir = 1 gives forward transform
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dir = -1 gives reverse transform
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*/
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long i,i1,j,k,i2,l,l1,l2;
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double c1,c2,tx,ty,t1,t2,u1,u2,z;
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int m=0, mm=1;
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/* get the exponent to the base of 2 from the number of points */
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while (mm < n) {
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mm *= 2;
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m++;
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}
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/* Do the bit reversal */
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i2 = n >> 1;
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j = 0;
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for (i=0;i<n-1;i++) {
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if (i < j) {
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tx = x[i];
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ty = y[i];
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x[i] = x[j];
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y[i] = y[j];
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x[j] = tx;
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y[j] = ty;
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}
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k = i2;
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while (k <= j) {
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j -= k;
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k >>= 1;
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}
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j += k;
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}
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/* Compute the FFT */
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c1 = -1.0;
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c2 = 0.0;
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l2 = 1;
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for (l=0;l<m;l++) {
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l1 = l2;
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l2 <<= 1;
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u1 = 1.0;
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u2 = 0.0;
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for (j=0;j<l1;j++) {
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for (i=j;i<n;i+=l2) {
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i1 = i + l1;
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t1 = u1 * x[i1] - u2 * y[i1];
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t2 = u1 * y[i1] + u2 * x[i1];
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x[i1] = x[i] - t1;
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y[i1] = y[i] - t2;
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x[i] += t1;
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y[i] += t2;
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}
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z = u1 * c1 - u2 * c2;
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u2 = u1 * c2 + u2 * c1;
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u1 = z;
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}
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c2 = sqrt((1.0 - c1) / 2.0);
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if (dir == 1)
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c2 = -c2;
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c1 = sqrt((1.0 + c1) / 2.0);
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}
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/* Scaling for forward transform */
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if (dir == 1) {
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for (i=0;i<n;i++) {
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x[i] /= n;
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y[i] /= n;
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}
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}
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}
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@ -0,0 +1,13 @@
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/*************
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* Header file for com_fft.c
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* 2008 H. Vogt
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************/
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#ifndef FFT_H_INCLUDED
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#define FFT_H_INCLUDED
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void com_fft(wordlist *wl);
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static void fftext(float*, float*, long int, int);
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#endif
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@ -256,6 +256,10 @@ struct comm spcp_coms[] = {
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{ 0, 0, 0, 0 }, E_DEFHMASK, 0, 0,
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(void (*)()) NULL,
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": Print a dump of the current circuit." } ,
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{ "fft", com_fft, FALSE, FALSE, TRUE,
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{ 0, 0, 0, 0 }, E_DEFHMASK, 1, LOTS,
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(void (*)()) NULL,
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"vector ... : Create a frequency domain plot with FFT." } ,
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{ "fourier", com_fourier, FALSE, FALSE, TRUE,
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{ 0, 040000, 040000, 040000 }, E_DEFHMASK, 1, LOTS,
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(void (*)()) NULL,
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@ -220,11 +220,12 @@ extern struct dvec *op_times();
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extern struct dvec *op_uminus();
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extern struct dvec *op_range();
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/* spec.c */
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extern void com_spec();
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/* com_fft.c */
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extern void com_fft(wordlist*);
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/* ginterface.c */
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extern bool gi_init();
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