qmckl/org/qmckl_utils.org

Utility functions

• Matrix operations
  • qmckl_transpose
    • Requirements
    • C header
    • Source

Matrix operations

qmckl_transpose

Transposes a matrix: $B_{ji} = A_{ij}$

qmckl_context	context	in	Global state
int64_t	m	in	Number of rows of the input matrix
int64_t	n	in	Number of columns of the input matrix
double	A[][lda]	in	Array containing the $m \times n$ matrix $A$
int64_t	lda	in	Leading dimension of array A
double	B[][ldb]	out	Array containing the $n \times m$ matrix $B$
int64_t	ldb	in	Leading dimension of array B

Requirements

• context is not QMCKL_NULL_CONTEXT
• m > 0
• n > 0
• lda >= m
• ldb >= n
• A is allocated with at least $m \times n \times 8$ bytes
• B is allocated with at least $n \times m \times 8$ bytes

C header

qmckl_exit_code qmckl_transpose (
      const qmckl_context context,
      const int64_t m,
      const int64_t n,
      const double* A,
      const int64_t lda,
      double* const B,
      const int64_t ldb );

Source

integer function qmckl_transpose_f(context, m, n, A, LDA, B, LDB) &
 result(info)
use qmckl
implicit none
integer(qmckl_context)  , intent(in)  :: context
integer*8  , intent(in)  :: m, n
integer*8  , intent(in)  :: lda
real*8     , intent(in)  :: A(lda,*)
integer*8  , intent(in)  :: ldb
real*8     , intent(out) :: B(ldb,*)

integer*8 :: i,j

info = QMCKL_SUCCESS

if (context == QMCKL_NULL_CONTEXT) then
 info = QMCKL_INVALID_CONTEXT
 return
endif

if (m <= 0_8) then
 info = QMCKL_INVALID_ARG_2
 return
endif

if (n <= 0_8) then
 info = QMCKL_INVALID_ARG_3
 return
endif

if (LDA < m) then
 info = QMCKL_INVALID_ARG_5
 return
endif

if (LDB < n) then
 info = QMCKL_INVALID_ARG_7
 return
endif

do j=1,m
 do i=1,n
   B(i,j) = A(j,i)
end do
end do

end function qmckl_transpose_f