diff options
Diffstat (limited to 'SRC/csycon_rook.f')
| -rw-r--r-- | SRC/csycon_rook.f | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/SRC/csycon_rook.f b/SRC/csycon_rook.f new file mode 100644 index 00000000..50690dfd --- /dev/null +++ b/SRC/csycon_rook.f @@ -0,0 +1,260 @@ +*> \brief \b CSYCON_ROOK +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +*> \htmlonly +*> Download CSYCON_ROOK + dependencies +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/csycon_rook.f"> +*> [TGZ]</a> +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/csycon_rook.f"> +*> [ZIP]</a> +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/csycon_rook.f"> +*> [TXT]</a> +*> \endhtmlonly +* +* Definition: +* =========== +* +* SUBROUTINE CSYCON_ROOK( UPLO, N, A, LDA, IPIV, ANORM, RCOND, +* WORK, IWORK, INFO ) +* +* .. Scalar Arguments .. +* CHARACTER UPLO +* INTEGER INFO, LDA, N +* REAL ANORM, RCOND +* .. +* .. Array Arguments .. +* INTEGER IPIV( * ), IWORK( * ) +* COMPLEX A( LDA, * ), WORK( * ) +* .. +* +* +*> \par Purpose: +* ============= +*> +*> \verbatim +*> +*> CSYCON_ROOK estimates the reciprocal of the condition number (in the +*> 1-norm) of a complex symmetric matrix A using the factorization +*> A = U*D*U**T or A = L*D*L**T computed by CSYTRF_ROOK. +*> +*> An estimate is obtained for norm(inv(A)), and the reciprocal of the +*> condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))). +*> \endverbatim +* +* Arguments: +* ========== +* +*> \param[in] UPLO +*> \verbatim +*> UPLO is CHARACTER*1 +*> Specifies whether the details of the factorization are stored +*> as an upper or lower triangular matrix. +*> = 'U': Upper triangular, form is A = U*D*U**T; +*> = 'L': Lower triangular, form is A = L*D*L**T. +*> \endverbatim +*> +*> \param[in] N +*> \verbatim +*> N is INTEGER +*> The order of the matrix A. N >= 0. +*> \endverbatim +*> +*> \param[in] A +*> \verbatim +*> A is COMPLEX array, dimension (LDA,N) +*> The block diagonal matrix D and the multipliers used to +*> obtain the factor U or L as computed by CSYTRF_ROOK. +*> \endverbatim +*> +*> \param[in] LDA +*> \verbatim +*> LDA is INTEGER +*> The leading dimension of the array A. LDA >= max(1,N). +*> \endverbatim +*> +*> \param[in] IPIV +*> \verbatim +*> IPIV is INTEGER array, dimension (N) +*> Details of the interchanges and the block structure of D +*> as determined by CSYTRF_ROOK. +*> \endverbatim +*> +*> \param[in] ANORM +*> \verbatim +*> ANORM is REAL +*> The 1-norm of the original matrix A. +*> \endverbatim +*> +*> \param[out] RCOND +*> \verbatim +*> RCOND is REAL +*> The reciprocal of the condition number of the matrix A, +*> computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an +*> estimate of the 1-norm of inv(A) computed in this routine. +*> \endverbatim +*> +*> \param[out] WORK +*> \verbatim +*> WORK is COMPLEX array, dimension (2*N) +*> \endverbatim +*> +*> \param[out] IWORK +*> \verbatim +*> IWORK is INTEGER array, dimension (N) +*> \endverbatim +*> +*> \param[out] INFO +*> \verbatim +*> INFO is INTEGER +*> = 0: successful exit +*> < 0: if INFO = -i, the i-th argument had an illegal value +*> \endverbatim +* +* Authors: +* ======== +* +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. +* +*> \date November 2011 +* +*> \ingroup complexSYcomputational +* +*> \par Contributors: +* ================== +*> \verbatim +*> +*> November 2011, Igor Kozachenko, +*> Computer Science Division, +*> University of California, Berkeley +*> +*> September 2007, Sven Hammarling, Nicholas J. Higham, Craig Lucas, +*> School of Mathematics, +*> University of Manchester +*> +*> \endverbatim +* +* ===================================================================== + SUBROUTINE CSYCON_ROOK( UPLO, N, A, LDA, IPIV, ANORM, RCOND, WORK, + $ IWORK, INFO ) +* +* -- LAPACK computational routine (version 3.4.0) -- +* -- LAPACK is a software package provided by Univ. of Tennessee, -- +* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- +* November 2011 +* +* .. Scalar Arguments .. + CHARACTER UPLO + INTEGER INFO, LDA, N + REAL ANORM, RCOND +* .. +* .. Array Arguments .. + INTEGER IPIV( * ), IWORK( * ) + COMPLEX A( LDA, * ), WORK( * ) +* .. +* +* ===================================================================== +* +* .. Parameters .. + REAL ONE, ZERO + PARAMETER ( ONE = 1.0E+0, ZERO = 0.0E+0 ) + COMPLEX CZERO + PARAMETER ( CZERO = ( 0.0E+0, 0.0E+0 ) ) +* .. +* .. Local Scalars .. + LOGICAL UPPER + INTEGER I, KASE + REAL AINVNM +* .. +* .. Local Arrays .. + INTEGER ISAVE( 3 ) +* .. +* .. External Functions .. + LOGICAL LSAME + EXTERNAL LSAME +* .. +* .. External Subroutines .. + EXTERNAL CLACN2, CSYTRS_ROOK, XERBLA +* .. +* .. Intrinsic Functions .. + INTRINSIC MAX +* .. +* .. Executable Statements .. +* +* Test the input parameters. +* + INFO = 0 + UPPER = LSAME( UPLO, 'U' ) + IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN + INFO = -1 + ELSE IF( N.LT.0 ) THEN + INFO = -2 + ELSE IF( LDA.LT.MAX( 1, N ) ) THEN + INFO = -4 + ELSE IF( ANORM.LT.ZERO ) THEN + INFO = -6 + END IF + IF( INFO.NE.0 ) THEN + CALL XERBLA( 'CSYCON_ROOK', -INFO ) + RETURN + END IF +* +* Quick return if possible +* + RCOND = ZERO + IF( N.EQ.0 ) THEN + RCOND = ONE + RETURN + ELSE IF( ANORM.LE.ZERO ) THEN + RETURN + END IF +* +* Check that the diagonal matrix D is nonsingular. +* + IF( UPPER ) THEN +* +* Upper triangular storage: examine D from bottom to top +* + DO 10 I = N, 1, -1 + IF( IPIV( I ).GT.0 .AND. A( I, I ).EQ.CZERO ) + $ RETURN + 10 CONTINUE + ELSE +* +* Lower triangular storage: examine D from top to bottom. +* + DO 20 I = 1, N + IF( IPIV( I ).GT.0 .AND. A( I, I ).EQ.CZERO ) + $ RETURN + 20 CONTINUE + END IF +* +* Estimate the 1-norm of the inverse. +* + KASE = 0 + 30 CONTINUE + CALL CLACN2( N, WORK( N+1 ), WORK, IWORK, AINVNM, KASE, ISAVE ) + IF( KASE.NE.0 ) THEN +* +* Multiply by inv(L*D*L**T) or inv(U*D*U**T). +* + CALL CSYTRS_ROOK( UPLO, N, 1, A, LDA, IPIV, WORK, N, INFO ) + GO TO 30 + END IF +* +* Compute the estimate of the reciprocal condition number. +* + IF( AINVNM.NE.ZERO ) + $ RCOND = ( ONE / AINVNM ) / ANORM +* + RETURN +* +* End of CSYCON_ROOK +* + END |