293 lines
8.4 KiB
C++
293 lines
8.4 KiB
C++
#include "Matrix.h"
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#include <iostream>
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#include <iomanip>
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//helper function to allocate memory for a matrix of size r x c and fill it with "fill"
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void Matrix::allocateMemory(unsigned int r, unsigned int c, double fill) {
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if(r == 0 || c == 0) {
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rows = 0;
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cols = 0;
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data = nullptr;
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return;
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}
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rows = r;
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cols = c;
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data = new double*[rows];
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for (unsigned int i = 0; i < rows; i++) {
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data[i] = new double[cols];
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for (unsigned int j = 0; j < cols; j++) {
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data[i][j] = fill;
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}
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}
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}
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//helper function to deallocate memory
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void Matrix::deallocateMemory() {
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if(data != nullptr) {
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for (unsigned int i = 0; i < rows; i++) {
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delete [] data[i];
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}
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delete [] data;
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data = nullptr;
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}
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rows = 0;
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cols = 0;
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}
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//default constructor: creates an empty 0 x 0 matrix
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Matrix::Matrix() : rows(0), cols(0), data(nullptr) { }
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//parameterized constructor
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Matrix::Matrix(unsigned int r, unsigned int c, double fill) : rows(0), cols(0), data(nullptr) {
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allocateMemory(r, c, fill);
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}
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//copy constructor
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Matrix::Matrix(const Matrix& other) : rows(0), cols(0), data(nullptr) {
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allocateMemory(other.rows, other.cols, 0.0);
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for (unsigned int i = 0; i < rows; i++) {
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for (unsigned int j = 0; j < cols; j++) {
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data[i][j] = other.data[i][j];
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}
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}
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}
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//destructor
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Matrix::~Matrix() {
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deallocateMemory();
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}
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//assignment operator
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Matrix& Matrix::operator=(const Matrix& other) {
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if (this == &other)
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return *this;
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deallocateMemory();
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allocateMemory(other.rows, other.cols, 0.0);
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for (unsigned int i = 0; i < rows; i++) {
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for (unsigned int j = 0; j < cols; j++) {
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data[i][j] = other.data[i][j];
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}
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}
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return *this;
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}
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//returns the number of rows
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unsigned int Matrix::num_rows() const {
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return rows;
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}
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//returns the number of columns
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unsigned int Matrix::num_cols() const {
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return cols;
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}
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//clears the matrix by deallocating its memory
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void Matrix::clear() {
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deallocateMemory();
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}
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bool Matrix::get(unsigned int row, unsigned int col, double &value) const {
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if(row >= rows || col >= cols) {
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return false;
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}
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value = data[row][col];
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return true;
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}
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//modifier
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bool Matrix::set(unsigned int row, unsigned int col, double value) {
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if(row >= rows || col >= cols) {
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return false;
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}
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data[row][col] = value;
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return true;
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}
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//equality operator
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bool Matrix::operator==(const Matrix& other) const {
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//two matrices are equal if dimensions match
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//and every element is equal within a small epsilon
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if(rows != other.rows || cols != other.cols)
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return false;
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for (unsigned int i = 0; i < rows; i++) {
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for (unsigned int j = 0; j < cols; j++) {
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if (fabs(data[i][j] - other.data[i][j]) > 1e-10)
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return false;
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}
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}
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return true;
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}
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bool Matrix::operator!=(const Matrix& other) const {
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return !(*this == other);
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}
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//multiplies every element by the given coefficient
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void Matrix::multiply_by_coefficient(double coeff) {
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for (unsigned int i = 0; i < rows; i++) {
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for (unsigned int j = 0; j < cols; j++) {
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data[i][j] *= coeff;
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}
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}
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}
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//swaps two rows of the matrix (by swapping the row pointers)
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bool Matrix::swap_row(unsigned int row1, unsigned int row2) {
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if(row1 >= rows || row2 >= rows) {
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return false;
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}
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double* temp = data[row1];
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data[row1] = data[row2];
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data[row2] = temp;
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return true;
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}
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//transposes the matrix in place
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void Matrix::transpose() {
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if(rows == 0 || cols == 0)
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return;
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unsigned int newRows = cols;
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unsigned int newCols = rows;
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double** newData = new double*[newRows];
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for (unsigned int i = 0; i < newRows; i++) {
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newData[i] = new double[newCols];
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for (unsigned int j = 0; j < newCols; j++) {
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newData[i][j] = data[j][i];
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}
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}
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deallocateMemory();
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rows = newRows;
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cols = newCols;
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data = newData;
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}
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//adds another matrix to this one element-wise
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bool Matrix::add(const Matrix& other) {
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if(rows != other.rows || cols != other.cols)
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return false;
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for (unsigned int i = 0; i < rows; i++) {
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for (unsigned int j = 0; j < cols; j++) {
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data[i][j] += other.data[i][j];
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}
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}
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return true;
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}
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//subtracts another matrix from this one element-wise
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bool Matrix::subtract(const Matrix& other) {
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if(rows != other.rows || cols != other.cols)
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return false;
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for (unsigned int i = 0; i < rows; i++) {
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for (unsigned int j = 0; j < cols; j++) {
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data[i][j] -= other.data[i][j];
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}
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}
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return true;
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}
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//returns a dynamically allocated copy of the specified row
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//caller must delete[] the returned array
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double* Matrix::get_row(unsigned int row) const {
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if(row >= rows)
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return NULL;
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double* rowArray = new double[cols];
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for (unsigned int j = 0; j < cols; j++) {
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rowArray[j] = data[row][j];
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}
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return rowArray;
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}
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//returns a dynamically allocated copy of the specified column
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//caller must delete[] the returned array
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double* Matrix::get_col(unsigned int col) const {
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if(col >= cols)
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return NULL;
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double* colArray = new double[rows];
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for (unsigned int i = 0; i < rows; i++) {
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colArray[i] = data[i][col];
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}
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return colArray;
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}
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//divides the matrix into four quadrants and returns a pointer to an array of four matrices
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//each quadrant size = ceil(rows/2) x ceil(cols/2)
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Matrix* Matrix::quarter() const {
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if (rows == 0 || cols == 0) {
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return nullptr;
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}
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// Determine quadrant size so that all four quadrants are identical.
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// For overlapping, use ceil for both dimensions.
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unsigned int q_rows = (rows % 2 == 0) ? (rows / 2) : (rows / 2 + 1);
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unsigned int q_cols = (cols % 2 == 0) ? (cols / 2) : (cols / 2 + 1);
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// For an overlapping quarter, the top quadrants start at row 0,
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// the bottom quadrants start at floor(rows/2), similarly for columns.
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unsigned int start_row_bottom = rows / 2;
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unsigned int start_col_right = cols / 2;
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Matrix* quadrants = new Matrix[4]{
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Matrix(q_rows, q_cols, 0.0), // Upper Left
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Matrix(q_rows, q_cols, 0.0), // Upper Right
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Matrix(q_rows, q_cols, 0.0), // Lower Left
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Matrix(q_rows, q_cols, 0.0) // Lower Right
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};
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// Fill Upper Left quadrant from original (starting at (0,0)).
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for (unsigned int i = 0; i < q_rows; i++) {
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for (unsigned int j = 0; j < q_cols; j++) {
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double value;
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if (i < rows && j < cols && get(i, j, value))
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quadrants[0].set(i, j, value);
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}
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}
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// Fill Upper Right quadrant from original (starting at (0, start_col_right)).
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for (unsigned int i = 0; i < q_rows; i++) {
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for (unsigned int j = 0; j < q_cols; j++) {
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double value;
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if (i < rows && (j + start_col_right) < cols && get(i, j + start_col_right, value))
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quadrants[1].set(i, j, value);
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}
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}
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// Fill Lower Left quadrant from original (starting at (start_row_bottom, 0)).
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for (unsigned int i = 0; i < q_rows; i++) {
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for (unsigned int j = 0; j < q_cols; j++) {
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double value;
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if ((i + start_row_bottom) < rows && j < cols && get(i + start_row_bottom, j, value))
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quadrants[2].set(i, j, value);
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}
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}
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// Fill Lower Right quadrant from original (starting at (start_row_bottom, start_col_right)).
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for (unsigned int i = 0; i < q_rows; i++) {
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for (unsigned int j = 0; j < q_cols; j++) {
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double value;
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if ((i + start_row_bottom) < rows && (j + start_col_right) < cols &&
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get(i + start_row_bottom, j + start_col_right, value))
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quadrants[3].set(i, j, value);
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}
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}
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return quadrants;
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}
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//overloaded output operator to print the matrix
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// 4 x 4 matrix:
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// [ 14 14 14 14
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// 14 14 14 14
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// 14 9 14 14
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// 14 14 14 13 ]
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std::ostream& operator<<(std::ostream& out, const Matrix& m) {
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out << m.rows << " x " << m.cols << " matrix:" << std::endl;
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out << "[ ";
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for (unsigned int i = 0; i < m.rows; i++) {
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for (unsigned int j = 0; j < m.cols; j++) {
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out << m.data[i][j];
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if(j < m.cols - 1)
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out << " ";
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}
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if(i < m.rows - 1)
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out << std::endl << " ";
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}
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out << " ]";
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return out;
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}
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