Annotation of rpl/lapack/lapack/zla_porcond_x.f, revision 1.1
1.1 ! bertrand 1: DOUBLE PRECISION FUNCTION ZLA_PORCOND_X( UPLO, N, A, LDA, AF,
! 2: $ LDAF, X, INFO, WORK,
! 3: $ RWORK )
! 4: *
! 5: * -- LAPACK routine (version 3.2.1) --
! 6: * -- Contributed by James Demmel, Deaglan Halligan, Yozo Hida and --
! 7: * -- Jason Riedy of Univ. of California Berkeley. --
! 8: * -- April 2009 --
! 9: *
! 10: * -- LAPACK is a software package provided by Univ. of Tennessee, --
! 11: * -- Univ. of California Berkeley and NAG Ltd. --
! 12: *
! 13: IMPLICIT NONE
! 14: * ..
! 15: * .. Scalar Arguments ..
! 16: CHARACTER UPLO
! 17: INTEGER N, LDA, LDAF, INFO
! 18: * ..
! 19: * .. Array Arguments ..
! 20: COMPLEX*16 A( LDA, * ), AF( LDAF, * ), WORK( * ), X( * )
! 21: DOUBLE PRECISION RWORK( * )
! 22: * ..
! 23: *
! 24: * Purpose
! 25: * =======
! 26: *
! 27: * ZLA_PORCOND_X Computes the infinity norm condition number of
! 28: * op(A) * diag(X) where X is a COMPLEX*16 vector.
! 29: *
! 30: * Arguments
! 31: * =========
! 32: *
! 33: * UPLO (input) CHARACTER*1
! 34: * = 'U': Upper triangle of A is stored;
! 35: * = 'L': Lower triangle of A is stored.
! 36: *
! 37: * N (input) INTEGER
! 38: * The number of linear equations, i.e., the order of the
! 39: * matrix A. N >= 0.
! 40: *
! 41: * A (input) COMPLEX*16 array, dimension (LDA,N)
! 42: * On entry, the N-by-N matrix A.
! 43: *
! 44: * LDA (input) INTEGER
! 45: * The leading dimension of the array A. LDA >= max(1,N).
! 46: *
! 47: * AF (input) COMPLEX*16 array, dimension (LDAF,N)
! 48: * The triangular factor U or L from the Cholesky factorization
! 49: * A = U**T*U or A = L*L**T, as computed by ZPOTRF.
! 50: *
! 51: * LDAF (input) INTEGER
! 52: * The leading dimension of the array AF. LDAF >= max(1,N).
! 53: *
! 54: * X (input) COMPLEX*16 array, dimension (N)
! 55: * The vector X in the formula op(A) * diag(X).
! 56: *
! 57: * INFO (output) INTEGER
! 58: * = 0: Successful exit.
! 59: * i > 0: The ith argument is invalid.
! 60: *
! 61: * WORK (input) COMPLEX*16 array, dimension (2*N).
! 62: * Workspace.
! 63: *
! 64: * RWORK (input) DOUBLE PRECISION array, dimension (N).
! 65: * Workspace.
! 66: *
! 67: * =====================================================================
! 68: *
! 69: * .. Local Scalars ..
! 70: INTEGER KASE, I, J
! 71: DOUBLE PRECISION AINVNM, ANORM, TMP
! 72: LOGICAL UP
! 73: COMPLEX*16 ZDUM
! 74: * ..
! 75: * .. Local Arrays ..
! 76: INTEGER ISAVE( 3 )
! 77: * ..
! 78: * .. External Functions ..
! 79: LOGICAL LSAME
! 80: EXTERNAL LSAME
! 81: * ..
! 82: * .. External Subroutines ..
! 83: EXTERNAL ZLACN2, ZPOTRS, XERBLA
! 84: * ..
! 85: * .. Intrinsic Functions ..
! 86: INTRINSIC ABS, MAX, REAL, DIMAG
! 87: * ..
! 88: * .. Statement Functions ..
! 89: DOUBLE PRECISION CABS1
! 90: * ..
! 91: * .. Statement Function Definitions ..
! 92: CABS1( ZDUM ) = ABS( DBLE( ZDUM ) ) + ABS( DIMAG( ZDUM ) )
! 93: * ..
! 94: * .. Executable Statements ..
! 95: *
! 96: ZLA_PORCOND_X = 0.0D+0
! 97: *
! 98: INFO = 0
! 99: IF( N.LT.0 ) THEN
! 100: INFO = -2
! 101: END IF
! 102: IF( INFO.NE.0 ) THEN
! 103: CALL XERBLA( 'ZLA_PORCOND_X', -INFO )
! 104: RETURN
! 105: END IF
! 106: UP = .FALSE.
! 107: IF ( LSAME( UPLO, 'U' ) ) UP = .TRUE.
! 108: *
! 109: * Compute norm of op(A)*op2(C).
! 110: *
! 111: ANORM = 0.0D+0
! 112: IF ( UP ) THEN
! 113: DO I = 1, N
! 114: TMP = 0.0D+0
! 115: DO J = 1, I
! 116: TMP = TMP + CABS1( A( J, I ) * X( J ) )
! 117: END DO
! 118: DO J = I+1, N
! 119: TMP = TMP + CABS1( A( I, J ) * X( J ) )
! 120: END DO
! 121: RWORK( I ) = TMP
! 122: ANORM = MAX( ANORM, TMP )
! 123: END DO
! 124: ELSE
! 125: DO I = 1, N
! 126: TMP = 0.0D+0
! 127: DO J = 1, I
! 128: TMP = TMP + CABS1( A( I, J ) * X( J ) )
! 129: END DO
! 130: DO J = I+1, N
! 131: TMP = TMP + CABS1( A( J, I ) * X( J ) )
! 132: END DO
! 133: RWORK( I ) = TMP
! 134: ANORM = MAX( ANORM, TMP )
! 135: END DO
! 136: END IF
! 137: *
! 138: * Quick return if possible.
! 139: *
! 140: IF( N.EQ.0 ) THEN
! 141: ZLA_PORCOND_X = 1.0D+0
! 142: RETURN
! 143: ELSE IF( ANORM .EQ. 0.0D+0 ) THEN
! 144: RETURN
! 145: END IF
! 146: *
! 147: * Estimate the norm of inv(op(A)).
! 148: *
! 149: AINVNM = 0.0D+0
! 150: *
! 151: KASE = 0
! 152: 10 CONTINUE
! 153: CALL ZLACN2( N, WORK( N+1 ), WORK, AINVNM, KASE, ISAVE )
! 154: IF( KASE.NE.0 ) THEN
! 155: IF( KASE.EQ.2 ) THEN
! 156: *
! 157: * Multiply by R.
! 158: *
! 159: DO I = 1, N
! 160: WORK( I ) = WORK( I ) * RWORK( I )
! 161: END DO
! 162: *
! 163: IF ( UP ) THEN
! 164: CALL ZPOTRS( 'U', N, 1, AF, LDAF,
! 165: $ WORK, N, INFO )
! 166: ELSE
! 167: CALL ZPOTRS( 'L', N, 1, AF, LDAF,
! 168: $ WORK, N, INFO )
! 169: ENDIF
! 170: *
! 171: * Multiply by inv(X).
! 172: *
! 173: DO I = 1, N
! 174: WORK( I ) = WORK( I ) / X( I )
! 175: END DO
! 176: ELSE
! 177: *
! 178: * Multiply by inv(X').
! 179: *
! 180: DO I = 1, N
! 181: WORK( I ) = WORK( I ) / X( I )
! 182: END DO
! 183: *
! 184: IF ( UP ) THEN
! 185: CALL ZPOTRS( 'U', N, 1, AF, LDAF,
! 186: $ WORK, N, INFO )
! 187: ELSE
! 188: CALL ZPOTRS( 'L', N, 1, AF, LDAF,
! 189: $ WORK, N, INFO )
! 190: END IF
! 191: *
! 192: * Multiply by R.
! 193: *
! 194: DO I = 1, N
! 195: WORK( I ) = WORK( I ) * RWORK( I )
! 196: END DO
! 197: END IF
! 198: GO TO 10
! 199: END IF
! 200: *
! 201: * Compute the estimate of the reciprocal condition number.
! 202: *
! 203: IF( AINVNM .NE. 0.0D+0 )
! 204: $ ZLA_PORCOND_X = 1.0D+0 / AINVNM
! 205: *
! 206: RETURN
! 207: *
! 208: END
CVSweb interface <joel.bertrand@systella.fr>
![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to zla_porcond_x.f CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [local] / rpl / lapack / lapack