dtrtrs (l) - Linux Man Pages
dtrtrs: solves a triangular system of the form A * X = B or A**T * X = B,
Command to display
dtrtrs manual in Linux:
$ man l dtrtrs
DTRTRS - solves a triangular system of the form A * X = B or A**T * X = B,
- SUBROUTINE DTRTRS(
UPLO, TRANS, DIAG, N, NRHS, A, LDA, B, LDB,
DIAG, TRANS, UPLO
INFO, LDA, LDB, N, NRHS
PRECISION A( LDA, * ), B( LDB, * )
DTRTRS solves a triangular system of the form
where A is a triangular matrix of order N, and B is an N-by-NRHS
matrix. A check is made to verify that A is nonsingular.
- UPLO (input) CHARACTER*1
= aqUaq: A is upper triangular;
= aqLaq: A is lower triangular.
- TRANS (input) CHARACTER*1
Specifies the form of the system of equations:
= aqNaq: A * X = B (No transpose)
= aqTaq: A**T * X = B (Transpose)
= aqCaq: A**H * X = B (Conjugate transpose = Transpose)
- DIAG (input) CHARACTER*1
= aqNaq: A is non-unit triangular;
= aqUaq: A is unit triangular.
- N (input) INTEGER
The order of the matrix A. N >= 0.
- NRHS (input) INTEGER
The number of right hand sides, i.e., the number of columns
of the matrix B. NRHS >= 0.
- A (input) DOUBLE PRECISION array, dimension (LDA,N)
The triangular matrix A. If UPLO = aqUaq, the leading N-by-N
upper triangular part of the array A contains the upper
triangular matrix, and the strictly lower triangular part of
A is not referenced. If UPLO = aqLaq, the leading N-by-N lower
triangular part of the array A contains the lower triangular
matrix, and the strictly upper triangular part of A is not
referenced. If DIAG = aqUaq, the diagonal elements of A are
also not referenced and are assumed to be 1.
- LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
- B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
On entry, the right hand side matrix B.
On exit, if INFO = 0, the solution matrix X.
- LDB (input) INTEGER
The leading dimension of the array B. LDB >= max(1,N).
- INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, the i-th diagonal element of A is zero,
indicating that the matrix is singular and the solutions
X have not been computed.
Pages related to dtrtrs
- dtrtrs (3)
- dtrtri (l) - computes the inverse of a real upper or lower triangular matrix A
- dtrti2 (l) - computes the inverse of a real upper or lower triangular matrix
- dtrttf (l) - copies a triangular matrix A from standard full format (TR) to rectangular full packed format (TF)
- dtrttp (l) - copies a triangular matrix A from full format (TR) to standard packed format (TP)
- dtrcon (l) - estimates the reciprocal of the condition number of a triangular matrix A, in either the 1-norm or the infinity-norm
- dtrevc (l) - computes some or all of the right and/or left eigenvectors of a real upper quasi-triangular matrix T
- dtrexc (l) - reorders the real Schur factorization of a real matrix A = Q*T*Q**T, so that the diagonal block of T with row index IFST is moved to row ILST