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Open Source Computer Vision Library
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126 lines
3.8 KiB
126 lines
3.8 KiB
#include "clapack.h" |
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/* Subroutine */ int sgesv_(integer *n, integer *nrhs, real *a, integer *lda, |
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integer *ipiv, 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 /* Subroutine */ int xerbla_(char *, integer *), sgetrf_( |
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integer *, integer *, real *, integer *, integer *, integer *), |
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sgetrs_(char *, integer *, integer *, real *, integer *, integer * |
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, real *, integer *, integer *); |
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/* -- LAPACK driver 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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/* SGESV computes the solution to a real system of linear equations */ |
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/* A * X = B, */ |
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/* where A is an N-by-N matrix and X and B are N-by-NRHS matrices. */ |
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/* The LU decomposition with partial pivoting and row interchanges is */ |
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/* used to factor A as */ |
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/* A = P * L * U, */ |
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/* where P is a permutation matrix, L is unit lower triangular, and U is */ |
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/* upper triangular. The factored form of A is then used to solve the */ |
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/* system of equations A * X = B. */ |
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/* Arguments */ |
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/* ========= */ |
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/* N (input) INTEGER */ |
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/* The number of linear equations, i.e., the order of the */ |
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/* 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/output) REAL array, dimension (LDA,N) */ |
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/* On entry, the N-by-N coefficient matrix A. */ |
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/* On exit, the factors L and U from the factorization */ |
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/* A = P*L*U; the unit diagonal elements of L are not stored. */ |
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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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/* IPIV (output) INTEGER array, dimension (N) */ |
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/* The pivot indices that define the permutation matrix P; */ |
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/* row i of the matrix was interchanged with row IPIV(i). */ |
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/* B (input/output) REAL array, dimension (LDB,NRHS) */ |
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/* On entry, the N-by-NRHS matrix of right hand side matrix B. */ |
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/* On exit, if INFO = 0, the N-by-NRHS 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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/* > 0: if INFO = i, U(i,i) is exactly zero. The factorization */ |
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/* has been completed, but the factor U is exactly */ |
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/* singular, so the solution could not be computed. */ |
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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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--ipiv; |
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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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if (*n < 0) { |
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*info = -1; |
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} else if (*nrhs < 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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} 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_("SGESV ", &i__1); |
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return 0; |
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} |
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/* Compute the LU factorization of A. */ |
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sgetrf_(n, n, &a[a_offset], lda, &ipiv[1], info); |
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if (*info == 0) { |
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/* Solve the system A*X = B, overwriting B with X. */ |
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sgetrs_("No transpose", n, nrhs, &a[a_offset], lda, &ipiv[1], &b[ |
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b_offset], ldb, info); |
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} |
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return 0; |
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/* End of SGESV */ |
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} /* sgesv_ */
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