#include "blaswrap.h" /* -- translated by f2c (version 19990503). You must link the resulting object file with the libraries: -lf2c -lm (in that order) */ #include "f2c.h" /* Table of constant values */ static real c_b9 = 1.f; /* Subroutine */ int sgeqrs_(integer *m, integer *n, integer *nrhs, real *a, integer *lda, real *tau, real *b, integer *ldb, real *work, integer * lwork, integer *info) { /* System generated locals */ integer a_dim1, a_offset, b_dim1, b_offset, i__1; /* Local variables */ extern /* Subroutine */ int strsm_(char *, char *, char *, char *, integer *, integer *, real *, real *, integer *, real *, integer * ), xerbla_(char *, integer *), sormqr_(char *, char *, integer *, integer *, integer *, real *, integer *, real *, real *, integer *, real *, integer *, integer *); /* -- LAPACK routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University February 29, 1992 Purpose ======= Solve the least squares problem min || A*X - B || using the QR factorization A = Q*R computed by SGEQRF. Arguments ========= M (input) INTEGER The number of rows of the matrix A. M >= 0. N (input) INTEGER The number of columns of the matrix A. M >= N >= 0. NRHS (input) INTEGER The number of columns of B. NRHS >= 0. A (input) REAL array, dimension (LDA,N) Details of the QR factorization of the original matrix A as returned by SGEQRF. LDA (input) INTEGER The leading dimension of the array A. LDA >= M. TAU (input) REAL array, dimension (N) Details of the orthogonal matrix Q. B (input/output) REAL array, dimension (LDB,NRHS) On entry, the m-by-nrhs right hand side matrix B. On exit, the n-by-nrhs solution matrix X. LDB (input) INTEGER The leading dimension of the array B. LDB >= M. WORK (workspace) REAL array, dimension (LWORK) LWORK (input) INTEGER The length of the array WORK. LWORK must be at least NRHS, and should be at least NRHS*NB, where NB is the block size for this environment. INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value ===================================================================== Test the input arguments. Parameter adjustments */ a_dim1 = *lda; a_offset = 1 + a_dim1 * 1; a -= a_offset; --tau; b_dim1 = *ldb; b_offset = 1 + b_dim1 * 1; b -= b_offset; --work; /* Function Body */ *info = 0; if (*m < 0) { *info = -1; } else if (*n < 0 || *n > *m) { *info = -2; } else if (*nrhs < 0) { *info = -3; } else if (*lda < max(1,*m)) { *info = -5; } else if (*ldb < max(1,*m)) { *info = -8; } else if (*lwork < 1 || *lwork < *nrhs && *m > 0 && *n > 0) { *info = -10; } if (*info != 0) { i__1 = -(*info); xerbla_("SGEQRS", &i__1); return 0; } /* Quick return if possible */ if (*n == 0 || *nrhs == 0 || *m == 0) { return 0; } /* B := Q' * B */ sormqr_("Left", "Transpose", m, nrhs, n, &a[a_offset], lda, &tau[1], &b[ b_offset], ldb, &work[1], lwork, info); /* Solve R*X = B(1:n,:) */ strsm_("Left", "Upper", "No transpose", "Non-unit", n, nrhs, &c_b9, &a[ a_offset], lda, &b[b_offset], ldb); return 0; /* End of SGEQRS */ } /* sgeqrs_ */