Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
p?trmv
Computes a distributed matrix-vector product using a triangular matrix.
Syntax
call pstrmv ( uplo , trans , diag , n , a , ia , ja , desca , x , ix , jx , descx , incx )
call pdtrmv ( uplo , trans , diag , n , a , ia , ja , desca , x , ix , jx , descx , incx )
call pctrmv ( uplo , trans , diag , n , a , ia , ja , desca , x , ix , jx , descx , incx )
call pztrmv ( uplo , trans , diag , n , a , ia , ja , desca , x , ix , jx , descx , incx )
Include Files
mkl_pblas.h
Description
The p?trmv routines perform one of the following distributed matrix-vector operations defined as
sub(x) := sub(A)*sub(x) , or sub(x) :=sub( A)'*sub(x) , or sub(x) := conjg(sub(A)')*sub(x) ,
where:
sub(A) is a n -by- n unit, or non-unit, upper or lower triangular distributed matrix, sub(A) = A(ia:ia+n-1, ja:ja+n-1) ,
sub(x) is an n -element distributed vector.
sub(x) denotes X(ix, jx:jx+n-1) if incx = m_x , and X(ix: ix+n-1, jx) if incx = 1,
Input Parameters
uplo
(global) CHARACTER*1 . Specifies whether the distributed matrix sub(A) is upper or lower triangular:
if uplo = 'U' or ‘u’ , then the matrix is upper triangular; if uplo = 'L' or ‘l’ , then the matrix is low triangular.
trans
(global) CHARACTER*1 . Specifies the form of op(sub(A)) used in the matrix equation:
if transa = 'N' or 'n' , then sub(x) := sub(A)*sub(x) ; if transa = 'T' or 't' , then sub(x) :=sub( A)'*sub(x) ; if transa = 'C' or 'c' , then sub(x) := conjg(sub(A)')*sub(x) .
diag
(global) CHARACTER*1 . Specifies whether the matrix sub(A) is unit triangular:
if diag = 'U' or ‘u’ then the matrix is unit triangular; if diag = 'N' or ‘n’ , then the matrix is not unit triangular.
n
(global) INTEGER . Specifies the order of the distributed matrix sub(A) , n ≥ 0.
a
(local) REAL for pstrmv
DOUBLE PRECISION for pdtrmv COMPLEX for pctrmv DOUBLE COMPLEX for pztrmv Array, size at least (lld_a, LOCq(1, ja+n-1)) . Before entry with uplo = 'U' or ‘u’ , this array contains the local entries corresponding to the entries of the upper triangular distributed matrix sub(A) , and the local entries corresponding to the entries of the strictly lower triangular part of the distributed matrix sub(A) is not referenced. Before entry with uplo = 'L' or ‘l’ , this array contains the local entries corresponding to the entries of the lower triangular distributed matrix sub(A) , and the local entries corresponding to the entries of the strictly upper triangular part of the distributed matrix sub(A) is not referenced . When diag = 'U' or ‘u’ , the local entries corresponding to the diagonal elements of the submatrix sub(A) are not referenced either, but are assumed to be unity.
ia , ja
(global) INTEGER . The row and column indices in the distributed matrix A indicating the first row and the first column of the submatrix sub(A) , respectively.
desca
(global and local) INTEGER array of dimension 9. The array descriptor of the distributed matrix A .
x
(local) REAL for pstrmv
DOUBLE PRECISION for pdtrmv COMPLEX for pctrmv DOUBLE COMPLEX for pztrmv Array, size at least (jx-1)*m_x + ix+(n-1)*abs(incx)) . This array contains the entries of the distributed vector sub(x) .
ix , jx
(global) INTEGER . The row and column indices in the distributed matrix X indicating the first row and the first column of the submatrix sub(x) , respectively.
descx
(global and local) INTEGER array of dimension 9. The array descriptor of the distributed matrix X .
incx
(global) INTEGER . Specifies the increment for the elements of sub(x) . Only two values are supported, namely 1 and m_x . incx must not be zero.
Output Parameters
- x
-
Overwritten by the transformed distributed vector sub(x) .