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45 lines
852 B
C
45 lines
852 B
C
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#include "hydrogen.h"
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#include "qmc_stats.h"
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#include <stdlib.h>
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#include <time.h>
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double uniform_montecarlo(double a, const int nmax) {
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double r[3], energy, norm, w, rnd;
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norm = 0.0;
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energy = 0.0;
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for (int i = 0; i < nmax; ++i) {
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for (int j = 0; j < 3; ++j) {
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rnd = (double) rand() / RAND_MAX;
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r[j] = -5.0 + 10.0 * rnd;
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}
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w = psi(a, r, 3) * psi(a, r, 3);
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norm += w;
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energy += w * e_loc(a, r, 3);
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}
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return energy / norm;
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}
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int main() {
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const double a = 1.2;
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const long nmax = 1e5;
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int nruns = 30;
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srand(time(NULL));
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double x[nruns], obs[2];
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for (int i = 0; i < nruns; ++i) {
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x[i] = uniform_montecarlo(a, nmax);
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}
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ave_error(x, nruns, obs);
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printf("E = %.5lf +/- %.5lf\n", obs[0], obs[1]);
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return 0;
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}
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