dtrsv
dtrsv - solve one of the systems of equations A*x = b, or A'*x = b
SUBROUTINE DTRSV( UPLO, TRANSA, DIAG, N, A, LDA, Y, INCY)
CHARACTER * 1 UPLO, TRANSA, DIAG
INTEGER N, LDA, INCY
DOUBLE PRECISION A(LDA,*), Y(*)
SUBROUTINE DTRSV_64( UPLO, TRANSA, DIAG, N, A, LDA, Y, INCY)
CHARACTER * 1 UPLO, TRANSA, DIAG
INTEGER*8 N, LDA, INCY
DOUBLE PRECISION A(LDA,*), Y(*)
SUBROUTINE TRSV( UPLO, [TRANSA], DIAG, [N], A, [LDA], Y, [INCY])
CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
INTEGER :: N, LDA, INCY
REAL(8), DIMENSION(:) :: Y
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE TRSV_64( UPLO, [TRANSA], DIAG, [N], A, [LDA], Y, [INCY])
CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
INTEGER(8) :: N, LDA, INCY
REAL(8), DIMENSION(:) :: Y
REAL(8), DIMENSION(:,:) :: A
#include <sunperf.h>
void dtrsv(char uplo, char transa, char diag, int n, double *a, int lda, double *y, int incy);
void dtrsv_64(char uplo, char transa, char diag, long n, double *a, long lda, double *y, long incy);
dtrsv solves one of the systems of equations
A*x = b, or A'*x = b,
where b and x are n element vectors and A is an n by n unit, or
non-unit, upper or lower triangular matrix.
No test for singularity or near-singularity is included in this
routine. Such tests must be performed before calling this routine.
-
* UPLO (input)
-
On entry, UPLO specifies whether the matrix is an upper or
lower triangular matrix as follows:
UPLO = 'U' or 'u' A is an upper triangular matrix.
UPLO = 'L' or 'l' A is a lower triangular matrix.
Unchanged on exit.
-
* TRANSA (input)
-
On entry, TRANSA specifies the equations to be solved as
follows:
TRANSA = 'N' or 'n' A*x = b.
TRANSA = 'T' or 't' A'*x = b.
TRANSA = 'C' or 'c' A'*x = b.
Unchanged on exit.
-
* DIAG (input)
-
On entry, DIAG specifies whether or not A is unit
triangular as follows:
DIAG = 'U' or 'u' A is assumed to be unit triangular.
DIAG = 'N' or 'n' A is not assumed to be unit
triangular.
Unchanged on exit.
-
* N (input)
-
On entry, N specifies the order of the matrix A.
N >= 0.
Unchanged on exit.
-
* A (input)
-
Before entry with UPLO = 'U' or 'u', the leading n by n
upper triangular part of the array A must contain the upper
triangular matrix and the strictly lower triangular part of
A is not referenced.
Before entry with UPLO = 'L' or 'l', the leading n by n
lower triangular part of the array A must contain the lower
triangular matrix and the strictly upper triangular part of
A is not referenced.
Note that when DIAG = 'U' or 'u', the diagonal elements of
A are not referenced either, but are assumed to be unity.
Unchanged on exit.
-
* LDA (input)
-
On entry, LDA specifies the first dimension of A as declared
in the calling (sub) program. LDA >= max( 1, n ).
Unchanged on exit.
-
* Y (input/output)
-
( 1 + ( n - 1 )*abs( INCY ) ).
Before entry, the incremented array Y must contain the n
element right-hand side vector b. On exit, Y is overwritten
with the solution vector x.
-
* INCY (input)
-
On entry, INCY specifies the increment for the elements of
Y. INCY <> 0.
Unchanged on exit.