matvecs.f90 Source File

submodule(specialmatrices_toeplitz) toeplitz_matvecs
   implicit none(type, external)
contains
   module procedure spmv
   integer(ilp) :: m, n
   real(dp), allocatable :: x_circ(:), y_circ(:)
   !> Dimension of the matrix.
   m = A%m; n = A%n
   !> Allocate variables.
   allocate (x_circ(m + n), source=0.0_dp); x_circ(:n) = x
   !> Toeplitz spmv via Circulant embedding.
   y_circ = matmul(Circulant(A), x_circ); y = y_circ(:m)
   end procedure spmv

   module procedure spmvs
   integer(ilp) :: m, n
   real(dp), allocatable :: x_circ(:, :), y_circ(:, :)
   !> Dimension of the matrix.
   m = A%m; n = A%n
   !> Allocate variables.
   allocate (x_circ(m + n, size(x, 2)), source=0.0_dp); x_circ(:n, :) = x
   !> Toeplitz spmv via Circulant embedding.
   y_circ = matmul(Circulant(A), x_circ); y = y_circ(:m, :)
   end procedure spmvs
end submodule toeplitz_matvecs