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103 lines
2.9 KiB
C++
103 lines
2.9 KiB
C++
// SM-MaponiA3_f.cpp
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// Algorithm 3 from P. Maponi,
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// p. 283, doi:10.1016/j.laa.2006.07.007
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#include "SM_MaponiA3.hpp"
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#include "Helpers.hpp"
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void MaponiA3(double *Slater0, double *Slater_inv, unsigned int M,
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unsigned int N_updates, double *Updates,
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unsigned int *Updates_index) {
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unsigned int k, l, lbar, i, j, tmp = M;
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unsigned int *p = new unsigned int[M + 1];
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double alpha, beta;
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double *breakdown = new double[M + 1];
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double *Al = new double[M * M];
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p[0] = 0;
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for (i = 0; i < M; i++) {
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p[i + 1] = i + 1;
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}
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// Declare auxiliary solution matrix ylk
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double ***ylk = new double **[M];
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for (l = 0; l < M; l++) {
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ylk[l] = new double *[M + 1];
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for (k = 0; k < M + 1; k++) {
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ylk[l][k] = new double[M + 1] {0};
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}
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}
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// Calculate all the y0k in M^2 multiplications instead of M^3
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for (k = 1; k < N_updates + 1; k++) {
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for (i = 1; i < M + 1; i++) {
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ylk[0][k][i] =
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Slater_inv[(i - 1) * M + (i - 1)] * Updates[(i - 1) * M + (k - 1)];
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}
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}
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// Calculate all the ylk from the y0k
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for (l = 1; l < M; l++) {
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for (j = l; j < M + 1; j++) {
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breakdown[j] = abs(1 + ylk[l - 1][p[j]][p[j]]);
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}
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lbar = getMaxIndex(breakdown, M + 1);
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tmp = p[l];
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p[l] = p[lbar];
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p[lbar] = tmp;
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for (k = l + 1; k < M + 1; k++) {
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beta = 1 + ylk[l - 1][p[l]][p[l]];
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if (beta == 0) {
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cout << "Break-down condition occured. Exiting..." << endl;
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exit;
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}
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for (i = 1; i < M + 1; i++) {
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alpha = ylk[l - 1][p[k]][p[l]] / beta;
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ylk[l][p[k]][i] = ylk[l - 1][p[k]][i] - alpha * ylk[l - 1][p[l]][i];
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}
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}
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}
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// Keep the memory location of the passed array 'Slater_inv' before
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// 'Slater_inv' gets reassigned by 'matMul(...)' in the next line, by creating
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// a new pointer 'copy' that points to whereever 'Slater_inv' points to now.
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double *copy = Slater_inv;
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// Construct A-inverse from A0-inverse and the ylk
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for (l = 0; l < M; l++) {
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k = l + 1;
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beta = 1 + ylk[l][p[k]][p[k]];
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for (i = 0; i < M; i++) {
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for (j = 0; j < M; j++) {
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Al[i * M + j] = (i == j) - (j == p[k]-1) * ylk[l][p[k]][i + 1] / beta;
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}
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}
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Slater_inv = matMul(Al, Slater_inv, M);
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}
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// Assign the new values of 'Slater_inv' to the old values in 'copy[][]'
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for (i = 0; i < M; i++) {
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for (j = 0; j < M; j++) {
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copy[i * M + j] = Slater_inv[i * M + j];
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}
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}
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for (l = 0; l < M; l++) {
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for (k = 0; k < M + 1; k++) {
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delete[] ylk[l][k];
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}
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delete[] ylk[l];
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}
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delete[] Al;
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delete[] p, breakdown;
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}
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extern "C" {
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void MaponiA3_f(double **linSlater0, double **linSlater_inv, unsigned int *Dim,
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unsigned int *N_updates, double **linUpdates,
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unsigned int **Updates_index) {
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MaponiA3(*linSlater0, *linSlater_inv, *Dim,
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*N_updates, *linUpdates,
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*Updates_index);
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}
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}
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