54 lines
1.3 KiB
C++
54 lines
1.3 KiB
C++
#ifndef _matvec_n_
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#define _matvec_n_
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#include "./utils/matrix.h"
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namespace numerics{
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// y = A * x, where A is (m×n) and x is length n and y is length m
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template <typename T>
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utils::Vector<T> matvec(const utils::Matrix<T>& A, const utils::Vector<T>& x) {
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if (A.cols() != x.size()) {
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throw std::runtime_error("matvec: dimension mismatch");
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}
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const uint64_t m = A.rows();
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const uint64_t n = A.cols();
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utils::Vector<T> y(m, T{0});
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for (uint64_t i = 0; i < m; ++i) {
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T acc = T{0};
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for (uint64_t j = 0; j < n; ++j) {
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acc += A(i, j) * x[j];
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}
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y[i] = acc;
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}
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return y;
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}
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// y = x * A, where x is length m and A is (m×n) -> y is length n
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template <typename T>
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utils::Vector<T> vecmat(const utils::Vector<T>& x, const utils::Matrix<T>& A) {
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if (x.size() != A.rows()) {
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throw std::runtime_error("vecmat: dimension mismatch");
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}
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const uint64_t m = A.rows();
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const uint64_t n = A.cols();
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utils::Vector<T> y(n, T{0});
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for (uint64_t j = 0; j < n; ++j) {
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T acc = T{0};
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for (uint64_t i = 0; i < m; ++i) {
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acc += x[i] * A(i, j);
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}
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y[j] = acc;
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}
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return y;
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}
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} // namespace numerics
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#endif // _matvec_n_
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