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151 lines
3.9 KiB
151 lines
3.9 KiB
#include "clapack.h" |
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/* Table of constant values */ |
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static real c_b9 = 1.f; |
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/* Subroutine */ int spotrs_(char *uplo, integer *n, integer *nrhs, real *a, |
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integer *lda, real *b, integer *ldb, integer *info) |
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{ |
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/* System generated locals */ |
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integer a_dim1, a_offset, b_dim1, b_offset, i__1; |
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/* Local variables */ |
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extern logical lsame_(char *, char *); |
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logical upper; |
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extern /* Subroutine */ int strsm_(char *, char *, char *, char *, |
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integer *, integer *, real *, real *, integer *, real *, integer * |
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), xerbla_(char *, 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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/* SPOTRS solves a system of linear equations A*X = B with a symmetric */ |
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/* positive definite matrix A using the Cholesky factorization */ |
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/* A = U**T*U or A = L*L**T computed by SPOTRF. */ |
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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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/* NRHS (input) INTEGER */ |
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/* The number of right hand sides, i.e., the number of columns */ |
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/* of the matrix B. NRHS >= 0. */ |
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/* A (input) REAL array, dimension (LDA,N) */ |
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/* The triangular factor U or L from the Cholesky factorization */ |
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/* A = U**T*U or A = L*L**T, as computed by SPOTRF. */ |
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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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/* B (input/output) REAL array, dimension (LDB,NRHS) */ |
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/* On entry, the right hand side matrix B. */ |
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/* On exit, the solution matrix X. */ |
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/* LDB (input) INTEGER */ |
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/* The leading dimension of the array B. LDB >= 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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/* ===================================================================== */ |
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/* .. Parameters .. */ |
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/* .. */ |
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/* .. Local Scalars .. */ |
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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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b_dim1 = *ldb; |
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b_offset = 1 + b_dim1; |
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b -= b_offset; |
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/* Function Body */ |
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*info = 0; |
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upper = lsame_(uplo, "U"); |
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if (! upper && ! 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 (*nrhs < 0) { |
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*info = -3; |
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} else if (*lda < max(1,*n)) { |
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*info = -5; |
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} else if (*ldb < max(1,*n)) { |
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*info = -7; |
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} |
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if (*info != 0) { |
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i__1 = -(*info); |
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xerbla_("SPOTRS", &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 || *nrhs == 0) { |
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return 0; |
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} |
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if (upper) { |
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/* Solve A*X = B where A = U'*U. */ |
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/* Solve U'*X = B, overwriting B with X. */ |
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strsm_("Left", "Upper", "Transpose", "Non-unit", n, nrhs, &c_b9, &a[ |
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a_offset], lda, &b[b_offset], ldb); |
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/* Solve U*X = B, overwriting B with X. */ |
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strsm_("Left", "Upper", "No transpose", "Non-unit", n, nrhs, &c_b9, & |
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a[a_offset], lda, &b[b_offset], ldb); |
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} else { |
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/* Solve A*X = B where A = L*L'. */ |
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/* Solve L*X = B, overwriting B with X. */ |
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strsm_("Left", "Lower", "No transpose", "Non-unit", n, nrhs, &c_b9, & |
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a[a_offset], lda, &b[b_offset], ldb); |
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/* Solve L'*X = B, overwriting B with X. */ |
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strsm_("Left", "Lower", "Transpose", "Non-unit", n, nrhs, &c_b9, &a[ |
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a_offset], lda, &b[b_offset], ldb); |
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} |
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return 0; |
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/* End of SPOTRS */ |
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} /* spotrs_ */
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