Sherman-Morrison/main.cpp

84 lines
2.4 KiB
C++

// Algorithm 3 from P. Maponi,
// p. 283, doi:10.1016/j.laa.2006.07.007
#include "SM-MaponiA3.hpp"
#include <cstdlib>
#include <ctime>
int main() {
srand((unsigned) time(0));
unsigned int randRange = 1; // to get random integers in range [-randRange, randRange]
unsigned int M = 3; // Dimension of the Slater-matrix
unsigned int i, j; // Indices for iterators
// Declare and allocate all vectors and matrices
unsigned int *Ar_index = new unsigned int[M];
int **A = new int*[M]; // The matrix to be inverted
int **A0 = new int*[M]; // A diagonal matrix with the digonal elements of A
int **Ar = new int*[M]; // The update matrix
double **A0_inv = new double*[M]; // Inverse of A0
for (i = 0; i < M; i++) {
A[i] = new int[M];
A0[i] = new int[M];
Ar[i] = new int[M];
A0_inv[i] = new double[M];
}
// Initialize all matrices with zeros
for (i = 0; i < M; i++) {
for (j = 0; j < M; j++) {
A0[i][j] = 0;
Ar[i][j] = 0;
A0_inv[i][j] = 0;
}
}
// Initialize A with M=3 and Eq. (17) from paper
A[0][0] = 1; A[0][1] = 1; A[0][2] = -1;
A[1][0] = 1; A[1][1] = 1; A[1][2] = 0;
A[2][0] = -1; A[2][1] = 0; A[2][2] = -1;
// // Fill A with random numbers from [-randRange,randRange]
// // and check if A and A0 are invertable
// do {
// for (i = 0; i < M; i++) {
// for (j = 0; j < M; j++) {
// A[i][j] = rand()%(2*randRange+1)-randRange;
// }
// }
// for (i = 0; i < M; i++) {
// A0[i][i] = A[i][i];
// }
// } while (matDet(A, M) == 0 || matDet(A0, M) == 0);
showMatrix(A, M, "A");
// Init the update matrix Ar, A0_inv and Ar_index
for (i = 0; i < M; i++) {
A0_inv[i][i] = 1.0/A[i][i];
Ar_index[i] = i;
for (j = 0; j < M; j++) {
Ar[i][j] = A[i][j] - A0[i][j];
}
}
unsigned int *dim = new unsigned int(M);
unsigned int *n_updates = new unsigned int(M);
Sherman_Morrison(A0, A0_inv, dim, n_updates, Ar, Ar_index);
showMatrix(A0_inv, M, "A0_inv");
// Deallocate all vectors and matrices
for (i = 0; i < M; i++) {
delete [] A[i];
delete [] A0[i];
delete [] A0_inv[i];
delete [] Ar[i];
}
delete [] A, A0, A0_inv, Ar, Ar_index;
delete dim, n_updates;
return 0;
}