00001 SUBROUTINE ZPOTRI( UPLO, N, A, LDA, INFO ) 00002 * 00003 * -- LAPACK routine (version 3.2) -- 00004 * -- LAPACK is a software package provided by Univ. of Tennessee, -- 00005 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- 00006 * November 2006 00007 * 00008 * .. Scalar Arguments .. 00009 CHARACTER UPLO 00010 INTEGER INFO, LDA, N 00011 * .. 00012 * .. Array Arguments .. 00013 COMPLEX*16 A( LDA, * ) 00014 * .. 00015 * 00016 * Purpose 00017 * ======= 00018 * 00019 * ZPOTRI computes the inverse of a complex Hermitian positive definite 00020 * matrix A using the Cholesky factorization A = U**H*U or A = L*L**H 00021 * computed by ZPOTRF. 00022 * 00023 * Arguments 00024 * ========= 00025 * 00026 * UPLO (input) CHARACTER*1 00027 * = 'U': Upper triangle of A is stored; 00028 * = 'L': Lower triangle of A is stored. 00029 * 00030 * N (input) INTEGER 00031 * The order of the matrix A. N >= 0. 00032 * 00033 * A (input/output) COMPLEX*16 array, dimension (LDA,N) 00034 * On entry, the triangular factor U or L from the Cholesky 00035 * factorization A = U**H*U or A = L*L**H, as computed by 00036 * ZPOTRF. 00037 * On exit, the upper or lower triangle of the (Hermitian) 00038 * inverse of A, overwriting the input factor U or L. 00039 * 00040 * LDA (input) INTEGER 00041 * The leading dimension of the array A. LDA >= max(1,N). 00042 * 00043 * INFO (output) INTEGER 00044 * = 0: successful exit 00045 * < 0: if INFO = -i, the i-th argument had an illegal value 00046 * > 0: if INFO = i, the (i,i) element of the factor U or L is 00047 * zero, and the inverse could not be computed. 00048 * 00049 * ===================================================================== 00050 * 00051 * .. External Functions .. 00052 LOGICAL LSAME 00053 EXTERNAL LSAME 00054 * .. 00055 * .. External Subroutines .. 00056 EXTERNAL XERBLA, ZLAUUM, ZTRTRI 00057 * .. 00058 * .. Intrinsic Functions .. 00059 INTRINSIC MAX 00060 * .. 00061 * .. Executable Statements .. 00062 * 00063 * Test the input parameters. 00064 * 00065 INFO = 0 00066 IF( .NOT.LSAME( UPLO, 'U' ) .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN 00067 INFO = -1 00068 ELSE IF( N.LT.0 ) THEN 00069 INFO = -2 00070 ELSE IF( LDA.LT.MAX( 1, N ) ) THEN 00071 INFO = -4 00072 END IF 00073 IF( INFO.NE.0 ) THEN 00074 CALL XERBLA( 'ZPOTRI', -INFO ) 00075 RETURN 00076 END IF 00077 * 00078 * Quick return if possible 00079 * 00080 IF( N.EQ.0 ) 00081 $ RETURN 00082 * 00083 * Invert the triangular Cholesky factor U or L. 00084 * 00085 CALL ZTRTRI( UPLO, 'Non-unit', N, A, LDA, INFO ) 00086 IF( INFO.GT.0 ) 00087 $ RETURN 00088 * 00089 * Form inv(U)*inv(U)' or inv(L)'*inv(L). 00090 * 00091 CALL ZLAUUM( UPLO, N, A, LDA, INFO ) 00092 * 00093 RETURN 00094 * 00095 * End of ZPOTRI 00096 * 00097 END
1.7.2