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112 lines
2.9 KiB
112 lines
2.9 KiB
#include "clapack.h" |
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/* Subroutine */ int dpotri_(char *uplo, integer *n, doublereal *a, integer * |
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lda, integer *info) |
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{ |
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/* System generated locals */ |
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integer a_dim1, a_offset, i__1; |
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/* Local variables */ |
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extern logical lsame_(char *, char *); |
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extern /* Subroutine */ int xerbla_(char *, integer *), dlauum_( |
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char *, integer *, doublereal *, integer *, integer *), |
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dtrtri_(char *, char *, integer *, doublereal *, integer *, |
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integer *); |
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/* -- LAPACK routine (version 3.1) -- */ |
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/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ |
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/* November 2006 */ |
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/* .. Scalar Arguments .. */ |
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/* .. */ |
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/* .. Array Arguments .. */ |
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/* .. */ |
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/* Purpose */ |
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/* ======= */ |
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/* DPOTRI computes the inverse of a real symmetric positive definite */ |
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/* matrix A using the Cholesky factorization A = U**T*U or A = L*L**T */ |
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/* computed by DPOTRF. */ |
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/* Arguments */ |
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/* ========= */ |
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/* UPLO (input) CHARACTER*1 */ |
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/* = 'U': Upper triangle of A is stored; */ |
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/* = 'L': Lower triangle of A is stored. */ |
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/* N (input) INTEGER */ |
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/* The order of the matrix A. N >= 0. */ |
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/* A (input/output) DOUBLE PRECISION array, dimension (LDA,N) */ |
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/* On entry, the triangular factor U or L from the Cholesky */ |
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/* factorization A = U**T*U or A = L*L**T, as computed by */ |
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/* DPOTRF. */ |
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/* On exit, the upper or lower triangle of the (symmetric) */ |
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/* inverse of A, overwriting the input factor U or L. */ |
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/* LDA (input) INTEGER */ |
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/* The leading dimension of the array A. LDA >= max(1,N). */ |
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/* INFO (output) INTEGER */ |
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/* = 0: successful exit */ |
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/* < 0: if INFO = -i, the i-th argument had an illegal value */ |
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/* > 0: if INFO = i, the (i,i) element of the factor U or L is */ |
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/* zero, and the inverse could not be computed. */ |
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/* ===================================================================== */ |
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/* .. External Functions .. */ |
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/* .. */ |
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/* .. External Subroutines .. */ |
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/* .. */ |
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/* .. Intrinsic Functions .. */ |
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/* .. */ |
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/* .. Executable Statements .. */ |
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/* Test the input parameters. */ |
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/* Parameter adjustments */ |
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a_dim1 = *lda; |
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a_offset = 1 + a_dim1; |
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a -= a_offset; |
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/* Function Body */ |
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*info = 0; |
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if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) { |
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*info = -1; |
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} else if (*n < 0) { |
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*info = -2; |
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} else if (*lda < max(1,*n)) { |
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*info = -4; |
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} |
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if (*info != 0) { |
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i__1 = -(*info); |
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xerbla_("DPOTRI", &i__1); |
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return 0; |
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} |
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/* Quick return if possible */ |
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if (*n == 0) { |
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return 0; |
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} |
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/* Invert the triangular Cholesky factor U or L. */ |
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dtrtri_(uplo, "Non-unit", n, &a[a_offset], lda, info); |
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if (*info > 0) { |
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return 0; |
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} |
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/* Form inv(U)*inv(U)' or inv(L)'*inv(L). */ |
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dlauum_(uplo, n, &a[a_offset], lda, info); |
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return 0; |
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/* End of DPOTRI */ |
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} /* dpotri_ */
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