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remove copy from phi_in to psi_out in evolve_wave

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Instead of copying phi_in to psi_out value by value in evolve_wave_half we
can redesign how we use our pointers and instead of copying everything we
can simply swap pointers afterwards. In some tests this resulted in a speed
up of ~10%
This commit is contained in:
Julian Kauth
2022-07-17 13:50:13 +02:00
parent d3ec9a57d2
commit 68d776b5e7
5 changed files with 56 additions and 88 deletions
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37
wave_billiard.c
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@@ -227,7 +227,7 @@ double courant2, courantb2; /* Courant parameters squared */
void evolve_wave_half(double *phi_in[NX], double *psi_in[NX], double *phi_out[NX], double *psi_out[NX],
void evolve_wave_half(double *phi_in[NX], double *psi_in[NX], double *phi_out[NX],
short int *xy_in[NX])
/* time step of field evolution */
/* phi is value of field at time t, psi at time t-1 */
@@ -277,7 +277,6 @@ void evolve_wave_half(double *phi_in[NX], double *psi_in[NX], double *phi_out[NX
/* evolve phi */
phi_out[i][j] = -y + 2*x + tcc[i][j]*delta - KAPPA*x - tgamma[i][j]*(x-y);
psi_out[i][j] = x;
}
}
}
@@ -315,7 +314,6 @@ void evolve_wave_half(double *phi_in[NX], double *psi_in[NX], double *phi_out[NX
break;
}
}
psi_out[0][j] = x;
}
}
@@ -351,7 +349,6 @@ void evolve_wave_half(double *phi_in[NX], double *psi_in[NX], double *phi_out[NX
break;
}
}
psi_out[NX-1][j] = x;
}
}
@@ -401,7 +398,6 @@ void evolve_wave_half(double *phi_in[NX], double *psi_in[NX], double *phi_out[NX
break;
}
}
psi_out[i][NY-1] = x;
}
}
@@ -451,7 +447,6 @@ void evolve_wave_half(double *phi_in[NX], double *psi_in[NX], double *phi_out[NX
break;
}
}
psi_out[i][0] = x;
}
}
@@ -469,20 +464,30 @@ void evolve_wave_half(double *phi_in[NX], double *psi_in[NX], double *phi_out[NX
{
if (phi_out[i][j] > VMAX) phi_out[i][j] = VMAX;
if (phi_out[i][j] < -VMAX) phi_out[i][j] = -VMAX;
if (psi_out[i][j] > VMAX) psi_out[i][j] = VMAX;
if (psi_out[i][j] < -VMAX) psi_out[i][j] = -VMAX;
}
}
}
}
void evolve_wave(double *phi[NX], double *psi[NX], double *phi_tmp[NX], double *psi_tmp[NX], short int *xy_in[NX])
void evolve_wave(double *phi[NX], double *psi[NX], double *tmp[NX], short int *xy_in[NX])
/* time step of field evolution */
/* phi is value of field at time t, psi at time t-1 */
{
evolve_wave_half(phi, psi, phi_tmp, psi_tmp, xy_in);
evolve_wave_half(phi_tmp, psi_tmp, phi, psi, xy_in);
// For the purpose of these comments w[t], w[t-1], w[t+1] are used to refer
// to phi, psi and the result respectively to avoid confusion with the
// passed parameter names.
// At the beginning w[t] is saved in phi, w[t-1] in psi and tmp is space
// for the next wave state w[t+1]. Take w[t] and w[t-1] to calculate the
// next wave state. Write this new state in temp
evolve_wave_half(phi, psi, tmp, xy_in);
// now w[t] is saved in tmp, w[t-1] in phi and the result is written to psi
evolve_wave_half(tmp, phi, psi, xy_in);
// now w[t] is saved in psi, w[t-1] in tmp and the result is written to phi
evolve_wave_half(psi, tmp, phi, xy_in);
// now w[t] is saved in phi, w[t-1] in psi and tmp is free again to take
// the new wave state w[t+1] in the next call to this function, thus
// matching the given parameter names again
}
@@ -514,7 +519,7 @@ void draw_color_bar_palette(int plot, double range, int palette, int fade, doubl
void animation()
{
double time, scale, ratio, startleft[2], startright[2], sign, r2, xy[2], fade_value;
double *phi[NX], *psi[NX], *phi_tmp[NX], *psi_tmp[NX], *total_energy[NX], *color_scale[NX];
double *phi[NX], *psi[NX], *tmp[NX], *total_energy[NX], *color_scale[NX];
short int *xy_in[NX];
int i, j, s, sample_left[2], sample_right[2], period = 0, fade;
static int counter = 0;
@@ -531,8 +536,7 @@ void animation()
{
phi[i] = (double *)malloc(NY*sizeof(double));
psi[i] = (double *)malloc(NY*sizeof(double));
phi_tmp[i] = (double *)malloc(NY*sizeof(double));
psi_tmp[i] = (double *)malloc(NY*sizeof(double));
tmp[i] = (double *)malloc(NY*sizeof(double));
total_energy[i] = (double *)malloc(NY*sizeof(double));
xy_in[i] = (short int *)malloc(NY*sizeof(short int));
color_scale[i] = (double *)malloc(NY*sizeof(double));
@@ -654,7 +658,7 @@ void animation()
else draw_wave_epalette(phi, psi, total_energy, color_scale, xy_in, scale, i, PLOT, COLOR_PALETTE, 0, 1.0);
for (j=0; j<NVID; j++)
{
evolve_wave(phi, psi, phi_tmp, psi_tmp, xy_in);
evolve_wave(phi, psi, tmp, xy_in);
if (SAVE_TIME_SERIES)
{
wave_value = (long int)(phi[sample_left[0]][sample_left[1]]*1.0e16);
@@ -760,8 +764,7 @@ void animation()
{
free(phi[i]);
free(psi[i]);
free(phi_tmp[i]);
free(psi_tmp[i]);
free(tmp[i]);
free(total_energy[i]);
free(xy_in[i]);
free(color_scale[i]);