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#include "matrix.hpp"
#include "linalg_error.hpp"
#include <algorithm>
#include <sstream>
#include <stdexcept>
namespace linalg {
namespace {
void check_same_shape(const Matrix& lhs, const Matrix& rhs, const char* operation) {
if (lhs.rows() != rhs.rows() || lhs.cols() != rhs.cols()) {
std::ostringstream oss;
oss << operation << " requires equal matrix shapes, got " << lhs.rows() << "x" << lhs.cols() << " and " << rhs.rows() << "x" << rhs.cols();
throw DimensionMismatchError(oss.str());
}
}
} // namespace
Matrix::Matrix(std::size_t rows, std::size_t cols)
: rows_(rows), cols_(cols), data_(rows * cols) {}
Matrix::Matrix(std::size_t rows, std::size_t cols, double value)
: rows_(rows), cols_(cols), data_(rows * cols, value) {}
Matrix::Matrix(std::initializer_list<std::initializer_list<double>> values) : rows_(values.size()) {
if (rows_ == 0) {
cols_ = 0;
return;
}
cols_ = values.begin()->size();
data_.reserve(rows_ * cols_);
for (const auto& row : values) {
if (row.size() != cols_) {
throw std::invalid_argument("Matrix initializer rows must have equal length");
}
data_.insert(data_.end(), row.begin(), row.end());
}
}
std::size_t Matrix::rows() const noexcept { return rows_; }
std::size_t Matrix::cols() const noexcept { return cols_; }
bool Matrix::empty() const noexcept { return data_.empty(); }
double& Matrix::operator()(std::size_t i, std::size_t j) {
check_bounds(i, j);
return data_[index(i, j)];
}
const double& Matrix::operator()(std::size_t i, std::size_t j) const {
check_bounds(i, j);
return data_[index(i, j)];
}
void Matrix::fill(double value) { std::fill(data_.begin(), data_.end(), value); }
double* Matrix::data() noexcept { return data_.data(); }
const double* Matrix::data() const noexcept { return data_.data(); }
Matrix Matrix::identity(std::size_t n) {
Matrix result(n, n);
for (std::size_t i = 0; i < n; ++i) {
result(i, i) = 1.0;
}
return result;
}
Matrix Matrix::zeros(std::size_t rows, std::size_t cols) { return Matrix(rows, cols, 0.0); }
std::size_t Matrix::index(std::size_t i, std::size_t j) const { return i * cols_ + j; }
void Matrix::check_bounds(std::size_t i, std::size_t j) const {
if (i >= rows_ || j >= cols_) {
throw std::out_of_range("Matrix index out of bounds");
}
}
Matrix transpose(const Matrix& matrix) {
Matrix result(matrix.cols(), matrix.rows());
for (std::size_t i = 0; i < matrix.rows(); ++i) {
for (std::size_t j = 0; j < matrix.cols(); ++j) {
result(j, i) = matrix(i, j);
}
}
return result;
}
Matrix operator+(const Matrix& lhs, const Matrix& rhs) {
check_same_shape(lhs, rhs, "Matrix addition");
Matrix result(lhs.rows(), lhs.cols());
for (std::size_t i = 0; i < lhs.rows(); ++i) {
for (std::size_t j = 0; j < lhs.cols(); ++j) {
result(i, j) = lhs(i, j) + rhs(i, j);
}
}
return result;
}
Matrix operator-(const Matrix& lhs, const Matrix& rhs) {
check_same_shape(lhs, rhs, "Matrix subtraction");
Matrix result(lhs.rows(), lhs.cols());
for (std::size_t i = 0; i < lhs.rows(); ++i) {
for (std::size_t j = 0; j < lhs.cols(); ++j) {
result(i, j) = lhs(i, j) - rhs(i, j);
}
}
return result;
}
Vector operator*(const Matrix& matrix, const Vector& vector) {
if (matrix.cols() != vector.size()) {
std::ostringstream oss;
oss << "Matrix-vector multiplication requires matrix columns to match vector size, got "
<< matrix.cols() << " and " << vector.size();
throw DimensionMismatchError(oss.str());
}
Vector result(matrix.rows());
for (std::size_t i = 0; i < matrix.rows(); ++i) {
double sum = 0.0;
for (std::size_t j = 0; j < matrix.cols(); ++j) {
sum += matrix(i, j) * vector[j];
}
result[i] = sum;
}
return result;
}
Matrix operator*(const Matrix& lhs, const Matrix& rhs) {
if (lhs.cols() != rhs.rows()) {
std::ostringstream oss;
oss << "Matrix multiplication requires lhs.cols() == rhs.rows(), got " << lhs.cols()
<< " and " << rhs.rows();
throw DimensionMismatchError(oss.str());
}
Matrix result(lhs.rows(), rhs.cols());
for (std::size_t i = 0; i < lhs.rows(); ++i) {
for (std::size_t k = 0; k < lhs.cols(); ++k) {
const double lhs_ik = lhs(i, k);
for (std::size_t j = 0; j < rhs.cols(); ++j) {
result(i, j) += lhs_ik * rhs(k, j);
}
}
}
return result;
}
} // namespace linalg
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