julie
be91086043
Those are just cosmetic changes to update version number and various other minor change.
150 lines
4.5 KiB
FortranFixed
150 lines
4.5 KiB
FortranFixed
SUBROUTINE CTRTRS( UPLO, TRANS, DIAG, N, NRHS, A, LDA, B, LDB,
|
|
$ INFO )
|
|
*
|
|
* -- LAPACK routine (version 3.2) --
|
|
* -- LAPACK is a software package provided by Univ. of Tennessee, --
|
|
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
|
|
* November 2006
|
|
*
|
|
* .. Scalar Arguments ..
|
|
CHARACTER DIAG, TRANS, UPLO
|
|
INTEGER INFO, LDA, LDB, N, NRHS
|
|
* ..
|
|
* .. Array Arguments ..
|
|
COMPLEX A( LDA, * ), B( LDB, * )
|
|
* ..
|
|
*
|
|
* 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.
|
|
*
|
|
* Arguments
|
|
* =========
|
|
*
|
|
* UPLO (input) CHARACTER*1
|
|
* = 'U': A is upper triangular;
|
|
* = 'L': A is lower triangular.
|
|
*
|
|
* TRANS (input) 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 (input) CHARACTER*1
|
|
* = 'N': A is non-unit triangular;
|
|
* = 'U': 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) 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 (input) INTEGER
|
|
* The leading dimension of the array A. LDA >= max(1,N).
|
|
*
|
|
* B (input/output) COMPLEX 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.
|
|
*
|
|
* =====================================================================
|
|
*
|
|
* .. Parameters ..
|
|
COMPLEX ZERO, ONE
|
|
PARAMETER ( ZERO = ( 0.0E+0, 0.0E+0 ),
|
|
$ ONE = ( 1.0E+0, 0.0E+0 ) )
|
|
* ..
|
|
* .. Local Scalars ..
|
|
LOGICAL NOUNIT
|
|
* ..
|
|
* .. External Functions ..
|
|
LOGICAL LSAME
|
|
EXTERNAL LSAME
|
|
* ..
|
|
* .. External Subroutines ..
|
|
EXTERNAL CTRSM, XERBLA
|
|
* ..
|
|
* .. Intrinsic Functions ..
|
|
INTRINSIC MAX
|
|
* ..
|
|
* .. Executable Statements ..
|
|
*
|
|
* Test the input parameters.
|
|
*
|
|
INFO = 0
|
|
NOUNIT = LSAME( DIAG, 'N' )
|
|
IF( .NOT.LSAME( UPLO, 'U' ) .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
|
|
INFO = -1
|
|
ELSE IF( .NOT.LSAME( TRANS, 'N' ) .AND. .NOT.
|
|
$ LSAME( TRANS, 'T' ) .AND. .NOT.LSAME( TRANS, 'C' ) ) THEN
|
|
INFO = -2
|
|
ELSE IF( .NOT.NOUNIT .AND. .NOT.LSAME( DIAG, 'U' ) ) THEN
|
|
INFO = -3
|
|
ELSE IF( N.LT.0 ) THEN
|
|
INFO = -4
|
|
ELSE IF( NRHS.LT.0 ) THEN
|
|
INFO = -5
|
|
ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
|
|
INFO = -7
|
|
ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
|
|
INFO = -9
|
|
END IF
|
|
IF( INFO.NE.0 ) THEN
|
|
CALL XERBLA( 'CTRTRS', -INFO )
|
|
RETURN
|
|
END IF
|
|
*
|
|
* Quick return if possible
|
|
*
|
|
IF( N.EQ.0 )
|
|
$ RETURN
|
|
*
|
|
* Check for singularity.
|
|
*
|
|
IF( NOUNIT ) THEN
|
|
DO 10 INFO = 1, N
|
|
IF( A( INFO, INFO ).EQ.ZERO )
|
|
$ RETURN
|
|
10 CONTINUE
|
|
END IF
|
|
INFO = 0
|
|
*
|
|
* Solve A * x = b, A**T * x = b, or A**H * x = b.
|
|
*
|
|
CALL CTRSM( 'Left', UPLO, TRANS, DIAG, N, NRHS, ONE, A, LDA, B,
|
|
$ LDB )
|
|
*
|
|
RETURN
|
|
*
|
|
* End of CTRTRS
|
|
*
|
|
END
|