Annotation of rpl/lapack/lapack/zla_porcond_c.f, revision 1.1
1.1 ! bertrand 1: DOUBLE PRECISION FUNCTION ZLA_PORCOND_C( UPLO, N, A, LDA, AF,
! 2: $ LDAF, C, CAPPLY, INFO,
! 3: $ WORK, 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: LOGICAL CAPPLY
! 18: INTEGER N, LDA, LDAF, INFO
! 19: * ..
! 20: * .. Array Arguments ..
! 21: COMPLEX*16 A( LDA, * ), AF( LDAF, * ), WORK( * )
! 22: DOUBLE PRECISION C( * ), RWORK( * )
! 23: * ..
! 24: *
! 25: * Purpose
! 26: * =======
! 27: *
! 28: * ZLA_PORCOND_C Computes the infinity norm condition number of
! 29: * op(A) * inv(diag(C)) where C is a DOUBLE PRECISION vector
! 30: *
! 31: * Arguments
! 32: * =========
! 33: *
! 34: * UPLO (input) CHARACTER*1
! 35: * = 'U': Upper triangle of A is stored;
! 36: * = 'L': Lower triangle of A is stored.
! 37: *
! 38: * N (input) INTEGER
! 39: * The number of linear equations, i.e., the order of the
! 40: * matrix A. N >= 0.
! 41: *
! 42: * A (input) COMPLEX*16 array, dimension (LDA,N)
! 43: * On entry, the N-by-N matrix A
! 44: *
! 45: * LDA (input) INTEGER
! 46: * The leading dimension of the array A. LDA >= max(1,N).
! 47: *
! 48: * AF (input) COMPLEX*16 array, dimension (LDAF,N)
! 49: * The triangular factor U or L from the Cholesky factorization
! 50: * A = U**T*U or A = L*L**T, as computed by ZPOTRF.
! 51: *
! 52: * LDAF (input) INTEGER
! 53: * The leading dimension of the array AF. LDAF >= max(1,N).
! 54: *
! 55: * C (input) DOUBLE PRECISION array, dimension (N)
! 56: * The vector C in the formula op(A) * inv(diag(C)).
! 57: *
! 58: * CAPPLY (input) LOGICAL
! 59: * If .TRUE. then access the vector C in the formula above.
! 60: *
! 61: * INFO (output) INTEGER
! 62: * = 0: Successful exit.
! 63: * i > 0: The ith argument is invalid.
! 64: *
! 65: * WORK (input) COMPLEX*16 array, dimension (2*N).
! 66: * Workspace.
! 67: *
! 68: * RWORK (input) DOUBLE PRECISION array, dimension (N).
! 69: * Workspace.
! 70: *
! 71: * =====================================================================
! 72: *
! 73: * .. Local Scalars ..
! 74: INTEGER KASE
! 75: DOUBLE PRECISION AINVNM, ANORM, TMP
! 76: INTEGER I, J
! 77: LOGICAL UP
! 78: COMPLEX*16 ZDUM
! 79: * ..
! 80: * .. Local Arrays ..
! 81: INTEGER ISAVE( 3 )
! 82: * ..
! 83: * .. External Functions ..
! 84: LOGICAL LSAME
! 85: EXTERNAL LSAME
! 86: * ..
! 87: * .. External Subroutines ..
! 88: EXTERNAL ZLACN2, ZPOTRS, XERBLA
! 89: * ..
! 90: * .. Intrinsic Functions ..
! 91: INTRINSIC ABS, MAX, REAL, DIMAG
! 92: * ..
! 93: * .. Statement Functions ..
! 94: DOUBLE PRECISION CABS1
! 95: * ..
! 96: * .. Statement Function Definitions ..
! 97: CABS1( ZDUM ) = ABS( DBLE( ZDUM ) ) + ABS( DIMAG( ZDUM ) )
! 98: * ..
! 99: * .. Executable Statements ..
! 100: *
! 101: ZLA_PORCOND_C = 0.0D+0
! 102: *
! 103: INFO = 0
! 104: IF( N.LT.0 ) THEN
! 105: INFO = -2
! 106: END IF
! 107: IF( INFO.NE.0 ) THEN
! 108: CALL XERBLA( 'ZLA_PORCOND_C', -INFO )
! 109: RETURN
! 110: END IF
! 111: UP = .FALSE.
! 112: IF ( LSAME( UPLO, 'U' ) ) UP = .TRUE.
! 113: *
! 114: * Compute norm of op(A)*op2(C).
! 115: *
! 116: ANORM = 0.0D+0
! 117: IF ( UP ) THEN
! 118: DO I = 1, N
! 119: TMP = 0.0D+0
! 120: IF ( CAPPLY ) THEN
! 121: DO J = 1, I
! 122: TMP = TMP + CABS1( A( J, I ) ) / C( J )
! 123: END DO
! 124: DO J = I+1, N
! 125: TMP = TMP + CABS1( A( I, J ) ) / C( J )
! 126: END DO
! 127: ELSE
! 128: DO J = 1, I
! 129: TMP = TMP + CABS1( A( J, I ) )
! 130: END DO
! 131: DO J = I+1, N
! 132: TMP = TMP + CABS1( A( I, J ) )
! 133: END DO
! 134: END IF
! 135: RWORK( I ) = TMP
! 136: ANORM = MAX( ANORM, TMP )
! 137: END DO
! 138: ELSE
! 139: DO I = 1, N
! 140: TMP = 0.0D+0
! 141: IF ( CAPPLY ) THEN
! 142: DO J = 1, I
! 143: TMP = TMP + CABS1( A( I, J ) ) / C( J )
! 144: END DO
! 145: DO J = I+1, N
! 146: TMP = TMP + CABS1( A( J, I ) ) / C( J )
! 147: END DO
! 148: ELSE
! 149: DO J = 1, I
! 150: TMP = TMP + CABS1( A( I, J ) )
! 151: END DO
! 152: DO J = I+1, N
! 153: TMP = TMP + CABS1( A( J, I ) )
! 154: END DO
! 155: END IF
! 156: RWORK( I ) = TMP
! 157: ANORM = MAX( ANORM, TMP )
! 158: END DO
! 159: END IF
! 160: *
! 161: * Quick return if possible.
! 162: *
! 163: IF( N.EQ.0 ) THEN
! 164: ZLA_PORCOND_C = 1.0D+0
! 165: RETURN
! 166: ELSE IF( ANORM .EQ. 0.0D+0 ) THEN
! 167: RETURN
! 168: END IF
! 169: *
! 170: * Estimate the norm of inv(op(A)).
! 171: *
! 172: AINVNM = 0.0D+0
! 173: *
! 174: KASE = 0
! 175: 10 CONTINUE
! 176: CALL ZLACN2( N, WORK( N+1 ), WORK, AINVNM, KASE, ISAVE )
! 177: IF( KASE.NE.0 ) THEN
! 178: IF( KASE.EQ.2 ) THEN
! 179: *
! 180: * Multiply by R.
! 181: *
! 182: DO I = 1, N
! 183: WORK( I ) = WORK( I ) * RWORK( I )
! 184: END DO
! 185: *
! 186: IF ( UP ) THEN
! 187: CALL ZPOTRS( 'U', N, 1, AF, LDAF,
! 188: $ WORK, N, INFO )
! 189: ELSE
! 190: CALL ZPOTRS( 'L', N, 1, AF, LDAF,
! 191: $ WORK, N, INFO )
! 192: ENDIF
! 193: *
! 194: * Multiply by inv(C).
! 195: *
! 196: IF ( CAPPLY ) THEN
! 197: DO I = 1, N
! 198: WORK( I ) = WORK( I ) * C( I )
! 199: END DO
! 200: END IF
! 201: ELSE
! 202: *
! 203: * Multiply by inv(C').
! 204: *
! 205: IF ( CAPPLY ) THEN
! 206: DO I = 1, N
! 207: WORK( I ) = WORK( I ) * C( I )
! 208: END DO
! 209: END IF
! 210: *
! 211: IF ( UP ) THEN
! 212: CALL ZPOTRS( 'U', N, 1, AF, LDAF,
! 213: $ WORK, N, INFO )
! 214: ELSE
! 215: CALL ZPOTRS( 'L', N, 1, AF, LDAF,
! 216: $ WORK, N, INFO )
! 217: END IF
! 218: *
! 219: * Multiply by R.
! 220: *
! 221: DO I = 1, N
! 222: WORK( I ) = WORK( I ) * RWORK( I )
! 223: END DO
! 224: END IF
! 225: GO TO 10
! 226: END IF
! 227: *
! 228: * Compute the estimate of the reciprocal condition number.
! 229: *
! 230: IF( AINVNM .NE. 0.0D+0 )
! 231: $ ZLA_PORCOND_C = 1.0D+0 / AINVNM
! 232: *
! 233: RETURN
! 234: *
! 235: END
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