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REAL FUNCTION CLA_PORCOND_C( UPLO, N, A, LDA, AF, LDAF, C, CAPPLY,
$ INFO, WORK, RWORK )
*
* -- LAPACK routine (version 3.2) --
* -- Contributed by James Demmel, Deaglan Halligan, Yozo Hida and --
* -- Jason Riedy of Univ. of California Berkeley. --
* -- November 2008 --
*
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley and NAG Ltd. --
*
IMPLICIT NONE
* ..
* .. Scalar Arguments ..
CHARACTER UPLO
LOGICAL CAPPLY
INTEGER N, LDA, LDAF, INFO
* ..
* .. Array Arguments ..
COMPLEX A( LDA, * ), AF( LDAF, * ), WORK( * )
REAL C( * ), RWORK( * )
* ..
*
* Purpose
* =======
*
* SLA_PORCOND_C Computes the infinity norm condition number of
* op(A) * inv(diag(C)) where C is a REAL vector
* WORK is a COMPLEX workspace of size 2*N, and
* RWORK is a REAL workspace of size 3*N.
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER KASE
REAL AINVNM, ANORM, TMP
INTEGER I, J
LOGICAL UP
COMPLEX ZDUM
* ..
* .. Local Arrays ..
INTEGER ISAVE( 3 )
* ..
* .. External Functions ..
LOGICAL LSAME
EXTERNAL LSAME
* ..
* .. External Subroutines ..
EXTERNAL CLACN2, CPOTRS, XERBLA
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS, MAX, REAL, AIMAG
* ..
* .. Statement Functions ..
REAL CABS1
* ..
* .. Statement Function Definitions ..
CABS1( ZDUM ) = ABS( REAL( ZDUM ) ) + ABS( AIMAG( ZDUM ) )
* ..
* .. Executable Statements ..
*
CLA_PORCOND_C = 0.0E+0
*
INFO = 0
IF( N.LT.0 ) THEN
INFO = -2
END IF
IF( INFO.NE.0 ) THEN
CALL XERBLA( 'CLA_PORCOND_C', -INFO )
RETURN
END IF
UP = .FALSE.
IF ( LSAME( UPLO, 'U' ) ) UP = .TRUE.
*
* Compute norm of op(A)*op2(C).
*
ANORM = 0.0E+0
IF ( UP ) THEN
DO I = 1, N
TMP = 0.0E+0
IF ( CAPPLY ) THEN
DO J = 1, N
IF ( I.GT.J ) THEN
TMP = TMP + CABS1( A( J, I ) ) / C( J )
ELSE
TMP = TMP + CABS1( A( I, J ) ) / C( J )
END IF
END DO
ELSE
DO J = 1, N
IF ( I.GT.J ) THEN
TMP = TMP + CABS1( A( J, I ) )
ELSE
TMP = TMP + CABS1( A( I, J ) )
END IF
END DO
END IF
RWORK( 2*N+I ) = TMP
ANORM = MAX( ANORM, TMP )
END DO
ELSE
DO I = 1, N
TMP = 0.0E+0
IF ( CAPPLY ) THEN
DO J = 1, N
IF ( I.LT.J ) THEN
TMP = TMP + CABS1( A( J, I ) ) / C( J )
ELSE
TMP = TMP + CABS1( A( I, J ) ) / C( J )
END IF
END DO
ELSE
DO J = 1, N
IF ( I.LT.J ) THEN
TMP = TMP + CABS1( A( J, I ) )
ELSE
TMP = TMP + CABS1( A( I, J ) )
END IF
END DO
END IF
RWORK( 2*N+I ) = TMP
ANORM = MAX( ANORM, TMP )
END DO
END IF
*
* Quick return if possible.
*
IF( N.EQ.0 ) THEN
CLA_PORCOND_C = 1.0E+0
RETURN
ELSE IF( ANORM .EQ. 0.0E+0 ) THEN
RETURN
END IF
*
* Estimate the norm of inv(op(A)).
*
AINVNM = 0.0E+0
*
KASE = 0
10 CONTINUE
CALL CLACN2( N, WORK( N+1 ), WORK, AINVNM, KASE, ISAVE )
IF( KASE.NE.0 ) THEN
IF( KASE.EQ.2 ) THEN
*
* Multiply by R.
*
DO I = 1, N
WORK( I ) = WORK( I ) * RWORK( 2*N+I )
END DO
*
IF ( UP ) THEN
CALL CPOTRS( 'U', N, 1, AF, LDAF,
$ WORK, N, INFO )
ELSE
CALL CPOTRS( 'L', N, 1, AF, LDAF,
$ WORK, N, INFO )
ENDIF
*
* Multiply by inv(C).
*
IF ( CAPPLY ) THEN
DO I = 1, N
WORK( I ) = WORK( I ) * C( I )
END DO
END IF
ELSE
*
* Multiply by inv(C').
*
IF ( CAPPLY ) THEN
DO I = 1, N
WORK( I ) = WORK( I ) * C( I )
END DO
END IF
*
IF ( UP ) THEN
CALL CPOTRS( 'U', N, 1, AF, LDAF,
$ WORK, N, INFO )
ELSE
CALL CPOTRS( 'L', N, 1, AF, LDAF,
$ WORK, N, INFO )
END IF
*
* Multiply by R.
*
DO I = 1, N
WORK( I ) = WORK( I ) * RWORK( 2*N+I )
END DO
END IF
GO TO 10
END IF
*
* Compute the estimate of the reciprocal condition number.
*
IF( AINVNM .NE. 0.0E+0 )
$ CLA_PORCOND_C = 1.0E+0 / AINVNM
*
RETURN
*
END
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