#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int sgelsx_(integer *m, integer *n, integer *nrhs, real *a, integer *lda, real *b, integer *ldb, integer *jpvt, real *rcond, integer *rank, real *work, integer *info) { /* -- LAPACK driver routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 Purpose ======= This routine is deprecated and has been replaced by routine SGELSY. SGELSX computes the minimum-norm solution to a real linear least squares problem: minimize || A * X - B || using a complete orthogonal factorization of A. A is an M-by-N matrix which may be rank-deficient. Several right hand side vectors b and solution vectors x can be handled in a single call; they are stored as the columns of the M-by-NRHS right hand side matrix B and the N-by-NRHS solution matrix X. The routine first computes a QR factorization with column pivoting: A * P = Q * [ R11 R12 ] [ 0 R22 ] with R11 defined as the largest leading submatrix whose estimated condition number is less than 1/RCOND. The order of R11, RANK, is the effective rank of A. Then, R22 is considered to be negligible, and R12 is annihilated by orthogonal transformations from the right, arriving at the complete orthogonal factorization: A * P = Q * [ T11 0 ] * Z [ 0 0 ] The minimum-norm solution is then X = P * Z' [ inv(T11)*Q1'*B ] [ 0 ] where Q1 consists of the first RANK columns of Q. 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. N >= 0. NRHS (input) INTEGER The number of right hand sides, i.e., the number of columns of matrices B and X. NRHS >= 0. A (input/output) REAL array, dimension (LDA,N) On entry, the M-by-N matrix A. On exit, A has been overwritten by details of its complete orthogonal factorization. LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,M). 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. If m >= n and RANK = n, the residual sum-of-squares for the solution in the i-th column is given by the sum of squares of elements N+1:M in that column. LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,M,N). JPVT (input/output) INTEGER array, dimension (N) On entry, if JPVT(i) .ne. 0, the i-th column of A is an initial column, otherwise it is a free column. Before the QR factorization of A, all initial columns are permuted to the leading positions; only the remaining free columns are moved as a result of column pivoting during the factorization. On exit, if JPVT(i) = k, then the i-th column of A*P was the k-th column of A. RCOND (input) REAL RCOND is used to determine the effective rank of A, which is defined as the order of the largest leading triangular submatrix R11 in the QR factorization with pivoting of A, whose estimated condition number < 1/RCOND. RANK (output) INTEGER The effective rank of A, i.e., the order of the submatrix R11. This is the same as the order of the submatrix T11 in the complete orthogonal factorization of A. WORK (workspace) REAL array, dimension (max( min(M,N)+3*N, 2*min(M,N)+NRHS )), INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value ===================================================================== Parameter adjustments */ /* Table of constant values */ static integer c__0 = 0; static real c_b13 = 0.f; static integer c__2 = 2; static integer c__1 = 1; static real c_b36 = 1.f; /* System generated locals */ integer a_dim1, a_offset, b_dim1, b_offset, i__1, i__2; real r__1; /* Local variables */ static integer i__, j, k; static real c1, c2, s1, s2, t1, t2; static integer mn; static real anrm, bnrm, smin, smax; static integer iascl, ibscl, ismin, ismax; extern /* Subroutine */ int strsm_(char *, char *, char *, char *, integer *, integer *, real *, real *, integer *, real *, integer * ), slaic1_(integer *, integer *, real *, real *, real *, real *, real *, real *, real *), sorm2r_( char *, char *, integer *, integer *, integer *, real *, integer * , real *, real *, integer *, real *, integer *), slabad_(real *, real *); extern doublereal slamch_(char *), slange_(char *, integer *, integer *, real *, integer *, real *); extern /* Subroutine */ int xerbla_(char *, integer *); static real bignum; extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, real *, integer *, integer *, real *, integer *, integer *), sgeqpf_(integer *, integer *, real *, integer *, integer *, real *, real *, integer *), slaset_(char *, integer *, integer *, real *, real *, real *, integer *); static real sminpr, smaxpr, smlnum; extern /* Subroutine */ int slatzm_(char *, integer *, integer *, real *, integer *, real *, real *, real *, integer *, real *), stzrqf_(integer *, integer *, real *, integer *, real *, integer * ); a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; b_dim1 = *ldb; b_offset = 1 + b_dim1; b -= b_offset; --jpvt; --work; /* Function Body */ mn = min(*m,*n); ismin = mn + 1; ismax = (mn << 1) + 1; /* Test the input arguments. */ *info = 0; if (*m < 0) { *info = -1; } else if (*n < 0) { *info = -2; } else if (*nrhs < 0) { *info = -3; } else if (*lda < max(1,*m)) { *info = -5; } else /* if(complicated condition) */ { /* Computing MAX */ i__1 = max(1,*m); if (*ldb < max(i__1,*n)) { *info = -7; } } if (*info != 0) { i__1 = -(*info); xerbla_("SGELSX", &i__1); return 0; } /* Quick return if possible Computing MIN */ i__1 = min(*m,*n); if (min(i__1,*nrhs) == 0) { *rank = 0; return 0; } /* Get machine parameters */ smlnum = slamch_("S") / slamch_("P"); bignum = 1.f / smlnum; slabad_(&smlnum, &bignum); /* Scale A, B if max elements outside range [SMLNUM,BIGNUM] */ anrm = slange_("M", m, n, &a[a_offset], lda, &work[1]); iascl = 0; if (anrm > 0.f && anrm < smlnum) { /* Scale matrix norm up to SMLNUM */ slascl_("G", &c__0, &c__0, &anrm, &smlnum, m, n, &a[a_offset], lda, info); iascl = 1; } else if (anrm > bignum) { /* Scale matrix norm down to BIGNUM */ slascl_("G", &c__0, &c__0, &anrm, &bignum, m, n, &a[a_offset], lda, info); iascl = 2; } else if (anrm == 0.f) { /* Matrix all zero. Return zero solution. */ i__1 = max(*m,*n); slaset_("F", &i__1, nrhs, &c_b13, &c_b13, &b[b_offset], ldb); *rank = 0; goto L100; } bnrm = slange_("M", m, nrhs, &b[b_offset], ldb, &work[1]); ibscl = 0; if (bnrm > 0.f && bnrm < smlnum) { /* Scale matrix norm up to SMLNUM */ slascl_("G", &c__0, &c__0, &bnrm, &smlnum, m, nrhs, &b[b_offset], ldb, info); ibscl = 1; } else if (bnrm > bignum) { /* Scale matrix norm down to BIGNUM */ slascl_("G", &c__0, &c__0, &bnrm, &bignum, m, nrhs, &b[b_offset], ldb, info); ibscl = 2; } /* Compute QR factorization with column pivoting of A: A * P = Q * R */ sgeqpf_(m, n, &a[a_offset], lda, &jpvt[1], &work[1], &work[mn + 1], info); /* workspace 3*N. Details of Householder rotations stored in WORK(1:MN). Determine RANK using incremental condition estimation */ work[ismin] = 1.f; work[ismax] = 1.f; smax = (r__1 = a[a_dim1 + 1], dabs(r__1)); smin = smax; if ((r__1 = a[a_dim1 + 1], dabs(r__1)) == 0.f) { *rank = 0; i__1 = max(*m,*n); slaset_("F", &i__1, nrhs, &c_b13, &c_b13, &b[b_offset], ldb); goto L100; } else { *rank = 1; } L10: if (*rank < mn) { i__ = *rank + 1; slaic1_(&c__2, rank, &work[ismin], &smin, &a[i__ * a_dim1 + 1], &a[ i__ + i__ * a_dim1], &sminpr, &s1, &c1); slaic1_(&c__1, rank, &work[ismax], &smax, &a[i__ * a_dim1 + 1], &a[ i__ + i__ * a_dim1], &smaxpr, &s2, &c2); if (smaxpr * *rcond <= sminpr) { i__1 = *rank; for (i__ = 1; i__ <= i__1; ++i__) { work[ismin + i__ - 1] = s1 * work[ismin + i__ - 1]; work[ismax + i__ - 1] = s2 * work[ismax + i__ - 1]; /* L20: */ } work[ismin + *rank] = c1; work[ismax + *rank] = c2; smin = sminpr; smax = smaxpr; ++(*rank); goto L10; } } /* Logically partition R = [ R11 R12 ] [ 0 R22 ] where R11 = R(1:RANK,1:RANK) [R11,R12] = [ T11, 0 ] * Y */ if (*rank < *n) { stzrqf_(rank, n, &a[a_offset], lda, &work[mn + 1], info); } /* Details of Householder rotations stored in WORK(MN+1:2*MN) B(1:M,1:NRHS) := Q' * B(1:M,1:NRHS) */ sorm2r_("Left", "Transpose", m, nrhs, &mn, &a[a_offset], lda, &work[1], & b[b_offset], ldb, &work[(mn << 1) + 1], info); /* workspace NRHS B(1:RANK,1:NRHS) := inv(T11) * B(1:RANK,1:NRHS) */ strsm_("Left", "Upper", "No transpose", "Non-unit", rank, nrhs, &c_b36, & a[a_offset], lda, &b[b_offset], ldb); i__1 = *n; for (i__ = *rank + 1; i__ <= i__1; ++i__) { i__2 = *nrhs; for (j = 1; j <= i__2; ++j) { b[i__ + j * b_dim1] = 0.f; /* L30: */ } /* L40: */ } /* B(1:N,1:NRHS) := Y' * B(1:N,1:NRHS) */ if (*rank < *n) { i__1 = *rank; for (i__ = 1; i__ <= i__1; ++i__) { i__2 = *n - *rank + 1; slatzm_("Left", &i__2, nrhs, &a[i__ + (*rank + 1) * a_dim1], lda, &work[mn + i__], &b[i__ + b_dim1], &b[*rank + 1 + b_dim1], ldb, &work[(mn << 1) + 1]); /* L50: */ } } /* workspace NRHS B(1:N,1:NRHS) := P * B(1:N,1:NRHS) */ i__1 = *nrhs; for (j = 1; j <= i__1; ++j) { i__2 = *n; for (i__ = 1; i__ <= i__2; ++i__) { work[(mn << 1) + i__] = 1.f; /* L60: */ } i__2 = *n; for (i__ = 1; i__ <= i__2; ++i__) { if (work[(mn << 1) + i__] == 1.f) { if (jpvt[i__] != i__) { k = i__; t1 = b[k + j * b_dim1]; t2 = b[jpvt[k] + j * b_dim1]; L70: b[jpvt[k] + j * b_dim1] = t1; work[(mn << 1) + k] = 0.f; t1 = t2; k = jpvt[k]; t2 = b[jpvt[k] + j * b_dim1]; if (jpvt[k] != i__) { goto L70; } b[i__ + j * b_dim1] = t1; work[(mn << 1) + k] = 0.f; } } /* L80: */ } /* L90: */ } /* Undo scaling */ if (iascl == 1) { slascl_("G", &c__0, &c__0, &anrm, &smlnum, n, nrhs, &b[b_offset], ldb, info); slascl_("U", &c__0, &c__0, &smlnum, &anrm, rank, rank, &a[a_offset], lda, info); } else if (iascl == 2) { slascl_("G", &c__0, &c__0, &anrm, &bignum, n, nrhs, &b[b_offset], ldb, info); slascl_("U", &c__0, &c__0, &bignum, &anrm, rank, rank, &a[a_offset], lda, info); } if (ibscl == 1) { slascl_("G", &c__0, &c__0, &smlnum, &bnrm, n, nrhs, &b[b_offset], ldb, info); } else if (ibscl == 2) { slascl_("G", &c__0, &c__0, &bignum, &bnrm, n, nrhs, &b[b_offset], ldb, info); } L100: return 0; /* End of SGELSX */ } /* sgelsx_ */