ctrtrs-f(3)

ctrtrs.f –

Synopsis

Functions/Subroutines

subroutine ctrtrs (UPLO, TRANS, DIAG, N, NRHS, A, LDA, B, LDB, INFO)
CTRTRS

Function/Subroutine Documentation

subroutine ctrtrs (characterUPLO, characterTRANS, characterDIAG, integerN, integerNRHS, complex, dimension( lda, * )A, integerLDA, complex, dimension( ldb, * )B, integerLDB, integerINFO)

CTRTRS

Purpose:

 CTRTRS solves a triangular system of the form
 A * X = B, A**T * X = B, or A**H * X = B,
 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.

Parameters:

UPLO

 UPLO is CHARACTER*1
 = 'U': A is upper triangular;
 = 'L': A is lower triangular.

TRANS

 TRANS is CHARACTER*1
 Specifies the form of the system of equations:
 = 'N': A * X = B (No transpose)
 = 'T': A**T * X = B (Transpose)
 = 'C': A**H * X = B (Conjugate transpose)

DIAG

 DIAG is CHARACTER*1
 = 'N': A is non-unit triangular;
 = 'U': A is unit triangular.

 N is INTEGER
 The order of the matrix A. N >= 0.

NRHS

 NRHS is INTEGER
 The number of right hand sides, i.e., the number of columns
 of the matrix B. NRHS >= 0.

 A is COMPLEX array, dimension (LDA,N)
 The triangular matrix A. If UPLO = 'U', 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 = 'L', 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 = 'U', the diagonal elements of A are
 also not referenced and are assumed to be 1.

LDA

 LDA is INTEGER
 The leading dimension of the array A. LDA >= max(1,N).

 B is COMPLEX array, dimension (LDB,NRHS)
 On entry, the right hand side matrix B.
 On exit, if INFO = 0, the solution matrix X.

LDB

 LDB is INTEGER
 The leading dimension of the array B. LDB >= max(1,N).

INFO

 INFO is 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.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 140 of file ctrtrs.f.

Author

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