Annotation of rpl/lapack/lapack/zlauum.f, revision 1.1
1.1 ! bertrand 1: SUBROUTINE ZLAUUM( UPLO, N, A, LDA, INFO )
! 2: *
! 3: * -- LAPACK auxiliary routine (version 3.2) --
! 4: * -- LAPACK is a software package provided by Univ. of Tennessee, --
! 5: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
! 6: * November 2006
! 7: *
! 8: * .. Scalar Arguments ..
! 9: CHARACTER UPLO
! 10: INTEGER INFO, LDA, N
! 11: * ..
! 12: * .. Array Arguments ..
! 13: COMPLEX*16 A( LDA, * )
! 14: * ..
! 15: *
! 16: * Purpose
! 17: * =======
! 18: *
! 19: * ZLAUUM computes the product U * U' or L' * L, where the triangular
! 20: * factor U or L is stored in the upper or lower triangular part of
! 21: * the array A.
! 22: *
! 23: * If UPLO = 'U' or 'u' then the upper triangle of the result is stored,
! 24: * overwriting the factor U in A.
! 25: * If UPLO = 'L' or 'l' then the lower triangle of the result is stored,
! 26: * overwriting the factor L in A.
! 27: *
! 28: * This is the blocked form of the algorithm, calling Level 3 BLAS.
! 29: *
! 30: * Arguments
! 31: * =========
! 32: *
! 33: * UPLO (input) CHARACTER*1
! 34: * Specifies whether the triangular factor stored in the array A
! 35: * is upper or lower triangular:
! 36: * = 'U': Upper triangular
! 37: * = 'L': Lower triangular
! 38: *
! 39: * N (input) INTEGER
! 40: * The order of the triangular factor U or L. N >= 0.
! 41: *
! 42: * A (input/output) COMPLEX*16 array, dimension (LDA,N)
! 43: * On entry, the triangular factor U or L.
! 44: * On exit, if UPLO = 'U', the upper triangle of A is
! 45: * overwritten with the upper triangle of the product U * U';
! 46: * if UPLO = 'L', the lower triangle of A is overwritten with
! 47: * the lower triangle of the product L' * L.
! 48: *
! 49: * LDA (input) INTEGER
! 50: * The leading dimension of the array A. LDA >= max(1,N).
! 51: *
! 52: * INFO (output) INTEGER
! 53: * = 0: successful exit
! 54: * < 0: if INFO = -k, the k-th argument had an illegal value
! 55: *
! 56: * =====================================================================
! 57: *
! 58: * .. Parameters ..
! 59: DOUBLE PRECISION ONE
! 60: PARAMETER ( ONE = 1.0D+0 )
! 61: COMPLEX*16 CONE
! 62: PARAMETER ( CONE = ( 1.0D+0, 0.0D+0 ) )
! 63: * ..
! 64: * .. Local Scalars ..
! 65: LOGICAL UPPER
! 66: INTEGER I, IB, NB
! 67: * ..
! 68: * .. External Functions ..
! 69: LOGICAL LSAME
! 70: INTEGER ILAENV
! 71: EXTERNAL LSAME, ILAENV
! 72: * ..
! 73: * .. External Subroutines ..
! 74: EXTERNAL XERBLA, ZGEMM, ZHERK, ZLAUU2, ZTRMM
! 75: * ..
! 76: * .. Intrinsic Functions ..
! 77: INTRINSIC MAX, MIN
! 78: * ..
! 79: * .. Executable Statements ..
! 80: *
! 81: * Test the input parameters.
! 82: *
! 83: INFO = 0
! 84: UPPER = LSAME( UPLO, 'U' )
! 85: IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
! 86: INFO = -1
! 87: ELSE IF( N.LT.0 ) THEN
! 88: INFO = -2
! 89: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
! 90: INFO = -4
! 91: END IF
! 92: IF( INFO.NE.0 ) THEN
! 93: CALL XERBLA( 'ZLAUUM', -INFO )
! 94: RETURN
! 95: END IF
! 96: *
! 97: * Quick return if possible
! 98: *
! 99: IF( N.EQ.0 )
! 100: $ RETURN
! 101: *
! 102: * Determine the block size for this environment.
! 103: *
! 104: NB = ILAENV( 1, 'ZLAUUM', UPLO, N, -1, -1, -1 )
! 105: *
! 106: IF( NB.LE.1 .OR. NB.GE.N ) THEN
! 107: *
! 108: * Use unblocked code
! 109: *
! 110: CALL ZLAUU2( UPLO, N, A, LDA, INFO )
! 111: ELSE
! 112: *
! 113: * Use blocked code
! 114: *
! 115: IF( UPPER ) THEN
! 116: *
! 117: * Compute the product U * U'.
! 118: *
! 119: DO 10 I = 1, N, NB
! 120: IB = MIN( NB, N-I+1 )
! 121: CALL ZTRMM( 'Right', 'Upper', 'Conjugate transpose',
! 122: $ 'Non-unit', I-1, IB, CONE, A( I, I ), LDA,
! 123: $ A( 1, I ), LDA )
! 124: CALL ZLAUU2( 'Upper', IB, A( I, I ), LDA, INFO )
! 125: IF( I+IB.LE.N ) THEN
! 126: CALL ZGEMM( 'No transpose', 'Conjugate transpose',
! 127: $ I-1, IB, N-I-IB+1, CONE, A( 1, I+IB ),
! 128: $ LDA, A( I, I+IB ), LDA, CONE, A( 1, I ),
! 129: $ LDA )
! 130: CALL ZHERK( 'Upper', 'No transpose', IB, N-I-IB+1,
! 131: $ ONE, A( I, I+IB ), LDA, ONE, A( I, I ),
! 132: $ LDA )
! 133: END IF
! 134: 10 CONTINUE
! 135: ELSE
! 136: *
! 137: * Compute the product L' * L.
! 138: *
! 139: DO 20 I = 1, N, NB
! 140: IB = MIN( NB, N-I+1 )
! 141: CALL ZTRMM( 'Left', 'Lower', 'Conjugate transpose',
! 142: $ 'Non-unit', IB, I-1, CONE, A( I, I ), LDA,
! 143: $ A( I, 1 ), LDA )
! 144: CALL ZLAUU2( 'Lower', IB, A( I, I ), LDA, INFO )
! 145: IF( I+IB.LE.N ) THEN
! 146: CALL ZGEMM( 'Conjugate transpose', 'No transpose', IB,
! 147: $ I-1, N-I-IB+1, CONE, A( I+IB, I ), LDA,
! 148: $ A( I+IB, 1 ), LDA, CONE, A( I, 1 ), LDA )
! 149: CALL ZHERK( 'Lower', 'Conjugate transpose', IB,
! 150: $ N-I-IB+1, ONE, A( I+IB, I ), LDA, ONE,
! 151: $ A( I, I ), LDA )
! 152: END IF
! 153: 20 CONTINUE
! 154: END IF
! 155: END IF
! 156: *
! 157: RETURN
! 158: *
! 159: * End of ZLAUUM
! 160: *
! 161: END
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