numkit-doxy/numerics_8hpp_source.html

// toolboxes/control/include/nk/control/internal/numerics.hpp

//

// Shared numerical kernels for toolboxes/control. All matrices are stored

// column-major in flat std::vector<double>.

//

// This header is INTERNAL — only toolboxes/control TUs include it. The

// kernels were originally inline-duplicated in response/discretize/

// freq/lyapunov/state, leading to ~4× the LU code, 2× the expm code

// and 2× the Faddeev char-poly code. Cycle 44 of the autonomous

// /loop consolidates them here. No behavioural change.


#pragma once


#include <cstddef>

#include <vector>


namespace nk::control::internal {


using Mat = std::vector<double>;

using Vec = std::vector<double>;


bool solveInPlace(Mat &A, Mat &B, std::size_t n, std::size_t nrhs);


Mat expm(const Mat &A, std::size_t n);


Vec charPoly(const Mat &A, std::size_t n);


Mat matmulSq(const Mat &A, const Mat &B, std::size_t n);


} // namespace nk::control::internal

nk::control::internal::solveInPlace
bool solveInPlace(Mat &A, Mat &B, std::size_t n, std::size_t nrhs)
In-place partial-pivot LU decomposition + back-substitution.

nk::control::internal::expm
Mat expm(const Mat &A, std::size_t n)
Matrix exponential via the canonical [6/6] Padé approximant with scaling and squaring.

nk::control::internal::matmulSq
Mat matmulSq(const Mat &A, const Mat &B, std::size_t n)
Square matrix multiply C = A·B (all n×n column-major).

nk::control::internal::charPoly
Vec charPoly(const Mat &A, std::size_t n)
Faddeev–LeVerrier characteristic polynomial of an n×n column-major matrix.