[PATCH] ipa: libipa: vector: Add matrix-vector multiplication

[Kieran Bingham]

Quoting Paul Elder (2024-06-07 09:20:45)
> Add an operation for multiplying a matrix with a vector.
> 
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> 
> ---
> Depends on v6 of "ipa: libipa: Add Matrix class" and v5 of "ipa: libipa:
> Add Vector class"
> ---
>  src/ipa/libipa/vector.cpp | 12 ++++++++++++
>  src/ipa/libipa/vector.h   | 22 ++++++++++++++++++++++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/src/ipa/libipa/vector.cpp b/src/ipa/libipa/vector.cpp
> index bdc3c447c..e18426fe5 100644
> --- a/src/ipa/libipa/vector.cpp
> +++ b/src/ipa/libipa/vector.cpp
> @@ -145,6 +145,18 @@ namespace ipa {
>   * \return The length of the vector
>   */
>  
> +/**
> + * \fn Vector<T, R1> operator*(const Matrix<T, R1, C1> &m, const Vector<T, R2> &v)
> + * \brief Multiply a matrix by a vector
> + * \tparam T Numerical type of the contents of the matrix and vector
> + * \tparam R1 The number of rows in the matrix
> + * \tparam C1 The number of colums in the matrix
> + * \tparam R2 The number of elements in the vector
> + * \param m The matrix
> + * \param v The vector
> + * \return Product of matrix \a m and vector \a v
> + */
> +
>  /**
>   * \fn bool operator==(const Vector<T, R> &lhs, const Vector<T, R> &rhs)
>   * \brief Compare vectors for equality
> diff --git a/src/ipa/libipa/vector.h b/src/ipa/libipa/vector.h
> index 87aad28b5..934b44494 100644
> --- a/src/ipa/libipa/vector.h
> +++ b/src/ipa/libipa/vector.h
> @@ -17,6 +17,8 @@
>  
>  #include "libcamera/internal/yaml_parser.h"
>  
> +#include "matrix.h"
> +
>  namespace libcamera {
>  
>  LOG_DECLARE_CATEGORY(Vector)
> @@ -166,6 +168,26 @@ private:
>         std::array<T, R> data_;
>  };
>  
> +#ifndef __DOXYGEN__
> +template<typename T,
> +        unsigned int R1, unsigned int C1,
> +        unsigned int R2,
> +        std::enable_if_t<std::is_arithmetic_v<T> && C1 == R2> * = nullptr>
> +#endif /* __DOXYGEN__ */
> +Vector<T, R1> operator*(const Matrix<T, R1, C1> &m, const Vector<T, R2> &v)
> +{
> +       Vector<T, R1> result;
> +

Does this need to ASSERT(C1 == R2); or such?

Other than that it looks ok to me, but I haven't seen the usage yet (or
tests :D)


Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>


> +       for (unsigned int i = 0; i < R1; i++) {
> +               T sum = 0;
> +               for (unsigned int j = 0; j < C1; j++)
> +                       sum += m[i][j] * v[j];
> +               result[i] = sum;
> +       }
> +
> +       return result;
> +}
> +
>  #ifndef __DOXYGEN__
>  template<typename T, unsigned int R,
>          std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
> -- 
> 2.39.2
>