106 lines
2.6 KiB
C++
106 lines
2.6 KiB
C++
#include "elimination.h"
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#include "matrix.h"
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#include "math.h"
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struct FracturedMatrix {
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Matrix A;
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ColumnVector C;
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ColumnVector b;
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int pivot_column_index;
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int pivot_row_index;
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};
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struct DestroyMatrix {
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Matrix A;
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ColumnVector C;
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ColumnVector b;
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};
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DestroyMatrix destroyGeneralMatrix(Matrix& generalMatrix) {
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int rows = generalMatrix.getRows();
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int cols = generalMatrix.getColumns();
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Matrix A(rows - 1, cols - 1);
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ColumnVector C(cols - 1);
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ColumnVector b(rows - 1);
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for (int j = 0; j < cols - 1; ++j) {
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C[j] = generalMatrix[0][j];
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}
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for (int i = 1; i < rows; ++i) {
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b[i - 1] = generalMatrix[i - 1][cols - 1];
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}
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for (int i = 1; i < rows; ++i) {
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for (int j = 0; j < cols - 1; ++j) {
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A[i - 1][j] = generalMatrix[i][j];
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}
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}
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return {A, C, b};
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}
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Matrix createGeneralMatrix(Matrix& A, ColumnVector& C, ColumnVector& b) {
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Matrix generalMatrix(A.getRows() + 1, A.getColumns() + 1);
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for (int i = 0; i < A.getColumns(); i++) {
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generalMatrix[0][i] = C[i];
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}
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for (int j = 0; j < A.getRows(); j++) {
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generalMatrix[j][A.getColumns()] = b[j];
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}
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for (int i = 0; i < A.getRows(); i++) {
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for (int j = 0; j < A.getColumns(); j++) {
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generalMatrix[i + 1][j] = A[i][j];
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}
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}
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return generalMatrix;
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}
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FracturedMatrix elimination(Matrix A, ColumnVector C, ColumnVector b, int pivot_column_index, int pivot_row_index) {
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Matrix generalMatrix = createGeneralMatrix(A, C, b);
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int rows = generalMatrix.getRows();
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int cols = generalMatrix.getColumns();
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double pivotElement = generalMatrix[pivot_row_index][pivot_column_index];
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for (int j = 0; j < cols; ++j) {
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generalMatrix[pivot_row_index][j] /= pivotElement;
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}
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for (int i = 0; i < rows; ++i) {
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if (i == pivot_row_index)
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continue;
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double pivotColumnCoefficient = generalMatrix[i][pivot_column_index];
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for (int j = 0; j < cols; ++j) {
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generalMatrix[i][j] -= pivotColumnCoefficient * generalMatrix[pivot_row_index][j];
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}
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}
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DestroyMatrix destroyedMatrix = destroyGeneralMatrix(generalMatrix);
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pivot_column_index = max_index(destroyedMatrix.C);
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ColumnVector ratio_vector(A.getRows());
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for (int i = 0; i < A.getRows(); i++) {
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if (A[i][pivot_column_index] != 0) {
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ratio_vector[i] = b[i] / A[i][pivot_column_index];
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}
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else {
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ratio_vector[i] = 0;
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}
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}
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int pivot_row_index = min_index(ratio_vector);
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return {A, C, b, pivot_column_index, pivot_row_index};
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}
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