Commit 8aedd0db authored by Matthieu Schaller's avatar Matthieu Schaller
Browse files

Used static arrays for the Ewald correction. Dump table to a file. Correction...

Used static arrays for the Ewald correction. Dump table to a file. Correction is within 1e-5 of the Gadget value.
parent 0d70e63d
......@@ -26,7 +26,7 @@ Statistics:
# Parameters for the self-gravity scheme
Gravity:
eta: 0.025 # Constant dimensionless multiplier for time integration.
epsilon: 0.0001 # Softening length (in internal units).
epsilon: 0.0000001 # Softening length (in internal units).
theta: 0.7 # Opening angle (Multipole acceptance criterion)
# Parameters for the hydrodynamics scheme
......
......@@ -26,6 +26,10 @@
#include <stdlib.h>
#include <unistd.h>
#ifdef HAVE_HDF5
#include <hdf5.h>
#endif
/* This object's header. */
#include "gravity.h"
......@@ -41,16 +45,19 @@ struct exact_force_data {
double const_G;
};
/* Components of the Ewald correction */
float *fewald_x;
float *fewald_y;
float *fewald_z;
#ifdef SWIFT_GRAVITY_FORCE_CHECKS
/* Size of the Ewald table */
const int N = 64;
#define Newald 64
/* Components of the Ewald correction */
static float fewald_x[Newald + 1][Newald + 1][Newald + 1];
static float fewald_y[Newald + 1][Newald + 1][Newald + 1];
static float fewald_z[Newald + 1][Newald + 1][Newald + 1];
/* Factor used to normalize the access to the Ewald table */
float ewald_fac;
#endif
/**
* @brief Allocates the memory and computes one octant of the
......@@ -78,42 +85,25 @@ void gravity_exact_force_ewald_init(double boxSize) {
const float factor_sin = 2.f * M_PI;
const float boxSize_inv2 = 1.f / (boxSize * boxSize);
/* Number of elements in each direction */
const int EN = N + 1;
/* Ewald factor to access the table */
ewald_fac = (double)(2 * EN) / boxSize;
/* Zero stuff before allocation */
fewald_x = NULL;
fewald_y = NULL;
fewald_z = NULL;
/* Allocate the correction arrays */
if ((posix_memalign((void **)&fewald_x, 64, EN * EN * EN * sizeof(float)) !=
0) ||
(posix_memalign((void **)&fewald_y, 64, EN * EN * EN * sizeof(float)) !=
0) ||
(posix_memalign((void **)&fewald_z, 64, EN * EN * EN * sizeof(float)) !=
0))
error("Error allocating array for Ewald correction");
ewald_fac = (double)(2 * Newald) / boxSize;
/* Zero everything */
bzero(fewald_x, EN * EN * EN * sizeof(float));
bzero(fewald_y, EN * EN * EN * sizeof(float));
bzero(fewald_z, EN * EN * EN * sizeof(float));
bzero(fewald_x, (Newald + 1) * (Newald + 1) * (Newald + 1) * sizeof(float));
bzero(fewald_y, (Newald + 1) * (Newald + 1) * (Newald + 1) * sizeof(float));
bzero(fewald_z, (Newald + 1) * (Newald + 1) * (Newald + 1) * sizeof(float));
/* Compute the values in one of the octants */
for (int i = 0; i < EN; ++i) {
for (int j = 0; j < EN; ++j) {
for (int k = 0; k < EN; ++k) {
for (int i = 0; i <= Newald; ++i) {
for (int j = 0; j <= Newald; ++j) {
for (int k = 0; k <= Newald; ++k) {
if (i == 0 && j == 0 && k == 0) continue;
/* Distance vector */
const float r_x = 0.5f * ((float)i) / N;
const float r_y = 0.5f * ((float)j) / N;
const float r_z = 0.5f * ((float)k) / N;
const float r_x = 0.5f * ((float)i) / Newald;
const float r_y = 0.5f * ((float)j) / Newald;
const float r_z = 0.5f * ((float)k) / Newald;
/* Norm of distance vector */
const float r2 = r_x * r_x + r_y * r_y + r_z * r_z;
......@@ -173,19 +163,51 @@ void gravity_exact_force_ewald_init(double boxSize) {
}
}
/* Apply the box-size correction */
f_x *= boxSize_inv2;
f_y *= boxSize_inv2;
f_z *= boxSize_inv2;
/* Save back to memory */
fewald_x[i * EN * EN + j * EN + k] = f_x;
fewald_y[i * EN * EN + j * EN + k] = f_y;
fewald_z[i * EN * EN + j * EN + k] = f_z;
fewald_x[i][j][k] = f_x;
fewald_y[i][j][k] = f_y;
fewald_z[i][j][k] = f_z;
}
}
}
/* Dump the Ewald table to a file */
#ifdef HAVE_HDF5
hid_t h_file = H5Fcreate("Ewald.hdf5", H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
if (h_file < 0)
error("Error while opening file for Ewald dump.");
/* Create dataspace */
hsize_t dim[3] = {Newald + 1, Newald + 1, Newald + 1};
hid_t h_space = H5Screate_simple(3, dim, NULL);
hid_t h_data;
h_data = H5Dcreate(h_file, "Ewald_x", H5T_NATIVE_FLOAT, h_space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
H5Dwrite(h_data, H5T_NATIVE_FLOAT, h_space, H5S_ALL, H5P_DEFAULT, &(fewald_x[0][0][0]));
H5Dclose(h_data);
h_data = H5Dcreate(h_file, "Ewald_y", H5T_NATIVE_FLOAT, h_space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
H5Dwrite(h_data, H5T_NATIVE_FLOAT, h_space, H5S_ALL, H5P_DEFAULT, &(fewald_y[0][0][0]));
H5Dclose(h_data);
h_data = H5Dcreate(h_file, "Ewald_z", H5T_NATIVE_FLOAT, h_space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
H5Dwrite(h_data, H5T_NATIVE_FLOAT, h_space, H5S_ALL, H5P_DEFAULT, &(fewald_z[0][0][0]));
H5Dclose(h_data);
H5Sclose(h_space);
H5Fclose(h_file);
#endif
//message("\n\n fewald_x[2 * EN * EN + 3 * EN + 4]=%e\n\n", fewald_x[2 * EN * EN + 3 * EN + 4]);
/* Apply the box-size correction */
for (int i = 0; i <= Newald; ++i) {
for (int j = 0; j <= Newald; ++j) {
for (int k = 0; k <= Newald; ++k) {
fewald_x[i][j][k] *= boxSize_inv2;
fewald_y[i][j][k] *= boxSize_inv2;
fewald_z[i][j][k] *= boxSize_inv2;
}
}
}
/* Say goodbye */
message("Ewald correction table computed (took %.3f %s). ",
clocks_from_ticks(getticks() - tic), clocks_getunit());
......@@ -222,62 +244,62 @@ __attribute__((always_inline)) INLINE static void
gravity_exact_force_ewald_evaluate(double rx, double ry, double rz,
double corr[3]) {
const int s_x = (rx < 0.) ? 1 : -1;
const int s_y = (ry < 0.) ? 1 : -1;
const int s_z = (rz < 0.) ? 1 : -1;
const double s_x = (rx < 0.) ? 1. : -1.;
const double s_y = (ry < 0.) ? 1. : -1.;
const double s_z = (rz < 0.) ? 1. : -1.;
rx = fabs(rx);
ry = fabs(ry);
rz = fabs(rz);
int i = (int)(rx * ewald_fac);
if (i >= N) i = N - 1;
if (i >= Newald) i = Newald - 1;
const double dx = rx * ewald_fac - i;
const double tx = 1. - dx;
int j = (int)(ry * ewald_fac);
if (j >= N) j = N - 1;
if (j >= Newald) j = Newald - 1;
const double dy = ry * ewald_fac - j;
const double ty = 1. - dy;
int k = (int)(rz * ewald_fac);
if (k >= N) k = N - 1;
if (k >= Newald) k = Newald - 1;
const double dz = rz * ewald_fac - k;
const double tz = 1. - dz;
/* Interpolation in X */
corr[0] = 0.;
corr[0] += fewald_x[(i + 0) * N * N + (j + 0) * N + (k + 0)] * tx * ty * tz;
corr[0] += fewald_x[(i + 0) * N * N + (j + 0) * N + (k + 1)] * tx * ty * dz;
corr[0] += fewald_x[(i + 0) * N * N + (j + 1) * N + (k + 0)] * tx * dy * tz;
corr[0] += fewald_x[(i + 0) * N * N + (j + 1) * N + (k + 1)] * tx * dy * dz;
corr[0] += fewald_x[(i + 1) * N * N + (j + 0) * N + (k + 0)] * dx * ty * tz;
corr[0] += fewald_x[(i + 1) * N * N + (j + 0) * N + (k + 1)] * dx * ty * dz;
corr[0] += fewald_x[(i + 1) * N * N + (j + 1) * N + (k + 0)] * dx * dy * tz;
corr[0] += fewald_x[(i + 1) * N * N + (j + 1) * N + (k + 1)] * dx * dy * dz;
corr[0] += fewald_x[i + 0][j + 0][k + 0] * tx * ty * tz;
corr[0] += fewald_x[i + 0][j + 0][k + 1] * tx * ty * dz;
corr[0] += fewald_x[i + 0][j + 1][k + 0] * tx * dy * tz;
corr[0] += fewald_x[i + 0][j + 1][k + 1] * tx * dy * dz;
corr[0] += fewald_x[i + 1][j + 0][k + 0] * dx * ty * tz;
corr[0] += fewald_x[i + 1][j + 0][k + 1] * dx * ty * dz;
corr[0] += fewald_x[i + 1][j + 1][k + 0] * dx * dy * tz;
corr[0] += fewald_x[i + 1][j + 1][k + 1] * dx * dy * dz;
corr[0] *= s_x;
/* Interpolation in Y */
corr[1] = 0.;
corr[1] += fewald_y[(i + 0) * N * N + (j + 0) * N + (k + 0)] * tx * ty * tz;
corr[1] += fewald_y[(i + 0) * N * N + (j + 0) * N + (k + 1)] * tx * ty * dz;
corr[1] += fewald_y[(i + 0) * N * N + (j + 1) * N + (k + 0)] * tx * dy * tz;
corr[1] += fewald_y[(i + 0) * N * N + (j + 1) * N + (k + 1)] * tx * dy * dz;
corr[1] += fewald_y[(i + 1) * N * N + (j + 0) * N + (k + 0)] * dx * ty * tz;
corr[1] += fewald_y[(i + 1) * N * N + (j + 0) * N + (k + 1)] * dx * ty * dz;
corr[1] += fewald_y[(i + 1) * N * N + (j + 1) * N + (k + 0)] * dx * dy * tz;
corr[1] += fewald_y[(i + 1) * N * N + (j + 1) * N + (k + 1)] * dx * dy * dz;
corr[1] += fewald_y[i + 0][j + 0][k + 0] * tx * ty * tz;
corr[1] += fewald_y[i + 0][j + 0][k + 1] * tx * ty * dz;
corr[1] += fewald_y[i + 0][j + 1][k + 0] * tx * dy * tz;
corr[1] += fewald_y[i + 0][j + 1][k + 1] * tx * dy * dz;
corr[1] += fewald_y[i + 1][j + 0][k + 0] * dx * ty * tz;
corr[1] += fewald_y[i + 1][j + 0][k + 1] * dx * ty * dz;
corr[1] += fewald_y[i + 1][j + 1][k + 0] * dx * dy * tz;
corr[1] += fewald_y[i + 1][j + 1][k + 1] * dx * dy * dz;
corr[1] *= s_y;
/* Interpolation in Z */
corr[2] = 0.;
corr[2] += fewald_z[(i + 0) * N * N + (j + 0) * N + (k + 0)] * tx * ty * tz;
corr[2] += fewald_z[(i + 0) * N * N + (j + 0) * N + (k + 1)] * tx * ty * dz;
corr[2] += fewald_z[(i + 0) * N * N + (j + 1) * N + (k + 0)] * tx * dy * tz;
corr[2] += fewald_z[(i + 0) * N * N + (j + 1) * N + (k + 1)] * tx * dy * dz;
corr[2] += fewald_z[(i + 1) * N * N + (j + 0) * N + (k + 0)] * dx * ty * tz;
corr[2] += fewald_z[(i + 1) * N * N + (j + 0) * N + (k + 1)] * dx * ty * dz;
corr[2] += fewald_z[(i + 1) * N * N + (j + 1) * N + (k + 0)] * dx * dy * tz;
corr[2] += fewald_z[(i + 1) * N * N + (j + 1) * N + (k + 1)] * dx * dy * dz;
corr[2] += fewald_z[i + 0][j + 0][k + 0] * tx * ty * tz;
corr[2] += fewald_z[i + 0][j + 0][k + 1] * tx * ty * dz;
corr[2] += fewald_z[i + 0][j + 1][k + 0] * tx * dy * tz;
corr[2] += fewald_z[i + 0][j + 1][k + 1] * tx * dy * dz;
corr[2] += fewald_z[i + 1][j + 0][k + 0] * dx * ty * tz;
corr[2] += fewald_z[i + 1][j + 0][k + 1] * dx * ty * dz;
corr[2] += fewald_z[i + 1][j + 1][k + 0] * dx * dy * tz;
corr[2] += fewald_z[i + 1][j + 1][k + 1] * dx * dy * dz;
corr[2] *= s_z;
}
......@@ -419,9 +441,9 @@ void gravity_exact_force_compute_mapper(void *map_data, int nr_gparts,
double corr[3];
gravity_exact_force_ewald_evaluate(dx, dy, dz, corr);
a_grav[0] += mj * corr[0] * 0.;
a_grav[1] += mj * corr[1] * 0.;
a_grav[2] += mj * corr[2] * 0.;
a_grav[0] += mj * corr[0];
a_grav[1] += mj * corr[1];
a_grav[2] += mj * corr[2];
}
}
......
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