/*
* The spectrum of a simple AM wave
*/
void am_wave(void) {
plot_t p;
p.outfile = "output3.png";
p.title = "AM wave";
p.xlabel = "t [s]";
p.ylabel = "u(t) [m]";
p.xmin = 0;
p.xmax = 0;
init_gnuplot(&p);
gsl_complex_packed_array data = calloc(2*N, sizeof(double));
BEGIN_SCATTER(p, "u(t)");
double t = 0;
for (int i = 0; i < 2*N; i += 2) {
data[i] = u(t);
PLOT(p, t, data[i]);
t += dt;
}
END_PLOT(p);
p.outfile = "output4.png";
p.title = "FFT of AM wave";
p.xlabel = "f [Hz]";
p.ylabel = "S(f) = |U(f)|^2 [m^2]";
p.xmin = 0;
p.xmax = 40;
init_gnuplot(&p);
gsl_fft_complex_radix2_forward(data, 1, N);
BEGIN_PLOT(p, "S(f)");
double f = 0;
for (int i = 0; i < N; i += 2) {
PLOT(p, f, (data[i]*data[i] + data[i+1]*data[i+1])/(N*N));
f += 1.0;
}
END_PLOT(p);
free(data);
}
int
main (int argc, char *argv[])
{
int i;
long seed = RAND_SEED;
for (i = 1; i < argc; i++) {
switch (*(argv[i] + 1)) {
case 'r':
seed = atoi (argv[++i]);
break;
default:
fprintf (stderr, "Usage : %s\n", argv[0]);
fprintf (stderr, "\t-r : random-seed(%ld)\n", seed);
exit (0);
break;
}
}
srand48 (seed);
init_1d_dk2011_bnf();
// set_1d_ordered_connection();
// test_symmetric_connections(1);
init_gnuplot ();
for (i = 0; i < N_LEARNING; i++) {
if (i % 10 == 0) {
sprintf (buf, "t=%d", i);
//plot3d_gnuplot (buf);
plot3d_gnuplot_file(buf,i);
}
one_cycle();
}
}
/*
* The Fourier transform of a Gaussian
*/
void gaussian(void) {
plot_t p;
p.outfile = "output1.png";
p.title = "Gaussian";
p.xlabel = "t [s]";
p.ylabel = "x(t) [m]";
p.xmin = -N/2*dt;
p.xmax = N/2*dt;
init_gnuplot(&p);
gsl_complex_packed_array data = calloc(2*N, sizeof(double));
BEGIN_SCATTER(p, "x(t)");
double t = -N/2 * dt;
for (int i = 0; i < 2*N; i += 2) {
data[i] = x(t);
PLOT(p, t, data[i]);
t += dt;
}
END_PLOT(p);
gsl_fft_complex_radix2_forward(data, 1, N);
p.outfile = "output2.png";
p.title = "FFT of a Gauissian";
p.xlabel = "f [Hz]";
p.ylabel = "X(f) [m]";
p.xmin = -512;
p.xmax = 512;
init_gnuplot(&p);
fprintf(p.fp, "plot '-' title 'Real',"
"'-' title 'Imag',"
"'-' with lines title 'Analytical'\n");
// Real part
double f = -1.0/(2.0*dt);
for (int i = N; i < 2*N; i += 2) {
PLOT(p, f, creal(shift(f))*(data[i]/(double) N));
f += 1.0;
}
for (int i = 0; i < N; i += 2) {
PLOT(p, f, creal(shift(f))*(data[i]/(double) N));
f += 1.0;
}
// Imag. part
NEW_PLOT(p);
f = -1.0/(2.0*dt);
for (int i = N+1; i <= 2*N; i += 2) {
PLOT(p, f, cimag(shift(f))*data[i]/(double) N);
f += 1.0;
}
for (int i = 1; i <= N; i += 2) {
PLOT(p, f, cimag(shift(f))*data[i]/(double) N);
f += 1.0;
}
// Analytical
NEW_PLOT(p);
f = -1.0/(2.0*dt);
for (int i = 1; i <= 2*N; i += 2) {
PLOT(p, f, X(f));
f += 1.0;
}
END_PLOT(p);
free(data);
}
/*
* Extracting information from a noisy signal
*/
void extract_noisy_signal(int count, double *values) {
plot_t p;
p.outfile = "output5.png";
p.title = "Noisy signal";
p.xlabel = "t [s]";
p.ylabel = "u(t) [m]";
p.xmin = 0;
p.xmax = 0;
init_gnuplot(&p);
gsl_complex_packed_array data = calloc(2*count, sizeof(double));
// Noisy signal
BEGIN_SCATTER(p, "u(t)");
double t = 0;
for (int i = 0; i < count; i++) {
PLOT(p, t, values[i]);
data[2*i] = values[i];
t += 1.0/count;
}
END_PLOT(p);
p.outfile = "output6.png";
p.title = "FFT of noisy signal";
p.xlabel = "f [Hz]";
p.ylabel = "U(f) [m]";
p.xmin = -1500;
p.xmax = 1500;
init_gnuplot(&p);
gsl_fft_complex_radix2_forward(data, 1, count);
// FFT of noisy signal
BEGIN_SCATTER(p, "U(f)");
double f = -count/2;
for (int i = count; i < 2*count; i += 2) {
double y = data[i];
data[i] = H(f) * data[i];
data[i+1] = H(f) * data[i+1];
PLOT(p, f, y);
f += 1.0;
}
for (int i = 0; i < count; i += 2) {
double y = data[i];
data[i] = H(f) * data[i];
data[i+1] = H(f) * data[i+1];
PLOT(p, f, y);
f += 1.0;
}
END_PLOT(p);
gsl_fft_complex_radix2_inverse(data, 1, count);
p.outfile = "output7.png";
p.title = "Inverse FFT of data";
p.xlabel = "t [s]";
p.ylabel = "u(t) [m]";
p.xmin = 0;
p.xmax = 1;
init_gnuplot(&p);
// Filtered signal
BEGIN_PLOT(p, "u(t)");
t = 0;
double umax = 0;
int periods = 0;
char letter = 0;
int bits = 0;
const double plen = 0.0078;
for (int i = 0; i < 2*count; i += 2) {
if (t >= plen * (double)periods && t < plen * ((double)periods + 1.0)) {
if (data[i] > umax) umax = data[i];
} else {
if (umax < 1) letter *= 2;
else letter = letter*2 + 1;
bits++;
if (bits % 8 == 0) {
printf("%c", letter);
bits = 0;
letter = 0;
}
umax = 0;
periods++;
}
PLOT(p, t, (data[i]));
t += 1.0/count;
}
if (umax < 1) letter *= 2;
else letter = letter*2 + 1;
printf("%c\n", letter);
END_PLOT(p);
}