Annotation of rpl/lapack/lapack/zpotri.f, revision 1.1
1.1 ! bertrand 1: SUBROUTINE ZPOTRI( UPLO, N, A, LDA, INFO )
! 2: *
! 3: * -- LAPACK 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: * ZPOTRI computes the inverse of a complex Hermitian positive definite
! 20: * matrix A using the Cholesky factorization A = U**H*U or A = L*L**H
! 21: * computed by ZPOTRF.
! 22: *
! 23: * Arguments
! 24: * =========
! 25: *
! 26: * UPLO (input) CHARACTER*1
! 27: * = 'U': Upper triangle of A is stored;
! 28: * = 'L': Lower triangle of A is stored.
! 29: *
! 30: * N (input) INTEGER
! 31: * The order of the matrix A. N >= 0.
! 32: *
! 33: * A (input/output) COMPLEX*16 array, dimension (LDA,N)
! 34: * On entry, the triangular factor U or L from the Cholesky
! 35: * factorization A = U**H*U or A = L*L**H, as computed by
! 36: * ZPOTRF.
! 37: * On exit, the upper or lower triangle of the (Hermitian)
! 38: * inverse of A, overwriting the input factor U or L.
! 39: *
! 40: * LDA (input) INTEGER
! 41: * The leading dimension of the array A. LDA >= max(1,N).
! 42: *
! 43: * INFO (output) INTEGER
! 44: * = 0: successful exit
! 45: * < 0: if INFO = -i, the i-th argument had an illegal value
! 46: * > 0: if INFO = i, the (i,i) element of the factor U or L is
! 47: * zero, and the inverse could not be computed.
! 48: *
! 49: * =====================================================================
! 50: *
! 51: * .. External Functions ..
! 52: LOGICAL LSAME
! 53: EXTERNAL LSAME
! 54: * ..
! 55: * .. External Subroutines ..
! 56: EXTERNAL XERBLA, ZLAUUM, ZTRTRI
! 57: * ..
! 58: * .. Intrinsic Functions ..
! 59: INTRINSIC MAX
! 60: * ..
! 61: * .. Executable Statements ..
! 62: *
! 63: * Test the input parameters.
! 64: *
! 65: INFO = 0
! 66: IF( .NOT.LSAME( UPLO, 'U' ) .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
! 67: INFO = -1
! 68: ELSE IF( N.LT.0 ) THEN
! 69: INFO = -2
! 70: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
! 71: INFO = -4
! 72: END IF
! 73: IF( INFO.NE.0 ) THEN
! 74: CALL XERBLA( 'ZPOTRI', -INFO )
! 75: RETURN
! 76: END IF
! 77: *
! 78: * Quick return if possible
! 79: *
! 80: IF( N.EQ.0 )
! 81: $ RETURN
! 82: *
! 83: * Invert the triangular Cholesky factor U or L.
! 84: *
! 85: CALL ZTRTRI( UPLO, 'Non-unit', N, A, LDA, INFO )
! 86: IF( INFO.GT.0 )
! 87: $ RETURN
! 88: *
! 89: * Form inv(U)*inv(U)' or inv(L)'*inv(L).
! 90: *
! 91: CALL ZLAUUM( UPLO, N, A, LDA, INFO )
! 92: *
! 93: RETURN
! 94: *
! 95: * End of ZPOTRI
! 96: *
! 97: END
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