Annotation of rpl/lapack/lapack/zhetri2.f, revision 1.1
1.1 ! bertrand 1: SUBROUTINE ZHETRI2( UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO )
! 2: *
! 3: * -- LAPACK routine (version 3.3.1) --
! 4: * -- LAPACK is a software package provided by Univ. of Tennessee, --
! 5: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
! 6: * -- April 2011 --
! 7: *
! 8: * -- Written by Julie Langou of the Univ. of TN --
! 9: *
! 10: * @precisions normal z -> c
! 11: *
! 12: * .. Scalar Arguments ..
! 13: CHARACTER UPLO
! 14: INTEGER INFO, LDA, LWORK, N
! 15: * ..
! 16: * .. Array Arguments ..
! 17: INTEGER IPIV( * )
! 18: COMPLEX*16 A( LDA, * ), WORK( * )
! 19: * ..
! 20: *
! 21: * Purpose
! 22: * =======
! 23: *
! 24: * ZHETRI2 computes the inverse of a COMPLEX*16 hermitian indefinite matrix
! 25: * A using the factorization A = U*D*U**T or A = L*D*L**T computed by
! 26: * ZHETRF. ZHETRI2 set the LEADING DIMENSION of the workspace
! 27: * before calling ZHETRI2X that actually computes the inverse.
! 28: *
! 29: * Arguments
! 30: * =========
! 31: *
! 32: * UPLO (input) CHARACTER*1
! 33: * Specifies whether the details of the factorization are stored
! 34: * as an upper or lower triangular matrix.
! 35: * = 'U': Upper triangular, form is A = U*D*U**T;
! 36: * = 'L': Lower triangular, form is A = L*D*L**T.
! 37: *
! 38: * N (input) INTEGER
! 39: * The order of the matrix A. N >= 0.
! 40: *
! 41: * A (input/output) COMPLEX*16 array, dimension (LDA,N)
! 42: * On entry, the NB diagonal matrix D and the multipliers
! 43: * used to obtain the factor U or L as computed by ZHETRF.
! 44: *
! 45: * On exit, if INFO = 0, the (symmetric) inverse of the original
! 46: * matrix. If UPLO = 'U', the upper triangular part of the
! 47: * inverse is formed and the part of A below the diagonal is not
! 48: * referenced; if UPLO = 'L' the lower triangular part of the
! 49: * inverse is formed and the part of A above the diagonal is
! 50: * not referenced.
! 51: *
! 52: * LDA (input) INTEGER
! 53: * The leading dimension of the array A. LDA >= max(1,N).
! 54: *
! 55: * IPIV (input) INTEGER array, dimension (N)
! 56: * Details of the interchanges and the NB structure of D
! 57: * as determined by ZHETRF.
! 58: *
! 59: * WORK (workspace) COMPLEX*16 array, dimension (N+NB+1)*(NB+3)
! 60: *
! 61: * LWORK (input) INTEGER
! 62: * The dimension of the array WORK.
! 63: * WORK is size >= (N+NB+1)*(NB+3)
! 64: * If LDWORK = -1, then a workspace query is assumed; the routine
! 65: * calculates:
! 66: * - the optimal size of the WORK array, returns
! 67: * this value as the first entry of the WORK array,
! 68: * - and no error message related to LDWORK is issued by XERBLA.
! 69: *
! 70: * INFO (output) INTEGER
! 71: * = 0: successful exit
! 72: * < 0: if INFO = -i, the i-th argument had an illegal value
! 73: * > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its
! 74: * inverse could not be computed.
! 75: *
! 76: * =====================================================================
! 77: *
! 78: * .. Local Scalars ..
! 79: LOGICAL UPPER, LQUERY
! 80: INTEGER MINSIZE, NBMAX
! 81: * ..
! 82: * .. External Functions ..
! 83: LOGICAL LSAME
! 84: INTEGER ILAENV
! 85: EXTERNAL LSAME, ILAENV
! 86: * ..
! 87: * .. External Subroutines ..
! 88: EXTERNAL ZHETRI2X
! 89: * ..
! 90: * .. Executable Statements ..
! 91: *
! 92: * Test the input parameters.
! 93: *
! 94: INFO = 0
! 95: UPPER = LSAME( UPLO, 'U' )
! 96: LQUERY = ( LWORK.EQ.-1 )
! 97: * Get blocksize
! 98: NBMAX = ILAENV( 1, 'ZHETRF', UPLO, N, -1, -1, -1 )
! 99: IF ( NBMAX .GE. N ) THEN
! 100: MINSIZE = N
! 101: ELSE
! 102: MINSIZE = (N+NBMAX+1)*(NBMAX+3)
! 103: END IF
! 104: *
! 105: IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
! 106: INFO = -1
! 107: ELSE IF( N.LT.0 ) THEN
! 108: INFO = -2
! 109: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
! 110: INFO = -4
! 111: ELSE IF (LWORK .LT. MINSIZE .AND. .NOT.LQUERY ) THEN
! 112: INFO = -7
! 113: END IF
! 114: *
! 115: * Quick return if possible
! 116: *
! 117: *
! 118: IF( INFO.NE.0 ) THEN
! 119: CALL XERBLA( 'ZHETRI2', -INFO )
! 120: RETURN
! 121: ELSE IF( LQUERY ) THEN
! 122: WORK(1)=MINSIZE
! 123: RETURN
! 124: END IF
! 125: IF( N.EQ.0 )
! 126: $ RETURN
! 127:
! 128: IF( NBMAX .GE. N ) THEN
! 129: CALL ZHETRI( UPLO, N, A, LDA, IPIV, WORK, INFO )
! 130: ELSE
! 131: CALL ZHETRI2X( UPLO, N, A, LDA, IPIV, WORK, NBMAX, INFO )
! 132: END IF
! 133: RETURN
! 134: *
! 135: * End of ZHETRI2
! 136: *
! 137: END
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