#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int dorm2l_(char *side, char *trans, integer *m, integer *n, integer *k, doublereal *a, integer *lda, doublereal *tau, doublereal * c__, integer *ldc, doublereal *work, integer *info) { /* -- LAPACK routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 Purpose ======= DORM2L overwrites the general real m by n matrix C with Q * C if SIDE = 'L' and TRANS = 'N', or Q'* C if SIDE = 'L' and TRANS = 'T', or C * Q if SIDE = 'R' and TRANS = 'N', or C * Q' if SIDE = 'R' and TRANS = 'T', where Q is a real orthogonal matrix defined as the product of k elementary reflectors Q = H(k) . . . H(2) H(1) as returned by DGEQLF. Q is of order m if SIDE = 'L' and of order n if SIDE = 'R'. Arguments ========= SIDE (input) CHARACTER*1 = 'L': apply Q or Q' from the Left = 'R': apply Q or Q' from the Right TRANS (input) CHARACTER*1 = 'N': apply Q (No transpose) = 'T': apply Q' (Transpose) M (input) INTEGER The number of rows of the matrix C. M >= 0. N (input) INTEGER The number of columns of the matrix C. N >= 0. K (input) INTEGER The number of elementary reflectors whose product defines the matrix Q. If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >= 0. A (input) DOUBLE PRECISION array, dimension (LDA,K) The i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DGEQLF in the last k columns of its array argument A. A is modified by the routine but restored on exit. LDA (input) INTEGER The leading dimension of the array A. If SIDE = 'L', LDA >= max(1,M); if SIDE = 'R', LDA >= max(1,N). TAU (input) DOUBLE PRECISION array, dimension (K) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by DGEQLF. C (input/output) DOUBLE PRECISION array, dimension (LDC,N) On entry, the m by n matrix C. On exit, C is overwritten by Q*C or Q'*C or C*Q' or C*Q. LDC (input) INTEGER The leading dimension of the array C. LDC >= max(1,M). WORK (workspace) DOUBLE PRECISION array, dimension (N) if SIDE = 'L', (M) if SIDE = 'R' INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value ===================================================================== Test the input arguments Parameter adjustments */ /* Table of constant values */ static integer c__1 = 1; /* System generated locals */ integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2; /* Local variables */ static integer i__, i1, i2, i3, mi, ni, nq; static doublereal aii; static logical left; extern /* Subroutine */ int dlarf_(char *, integer *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *, doublereal *); extern logical lsame_(char *, char *); extern /* Subroutine */ int xerbla_(char *, integer *); static logical notran; a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; --tau; c_dim1 = *ldc; c_offset = 1 + c_dim1; c__ -= c_offset; --work; /* Function Body */ *info = 0; left = lsame_(side, "L"); notran = lsame_(trans, "N"); /* NQ is the order of Q */ if (left) { nq = *m; } else { nq = *n; } if (! left && ! lsame_(side, "R")) { *info = -1; } else if (! notran && ! lsame_(trans, "T")) { *info = -2; } else if (*m < 0) { *info = -3; } else if (*n < 0) { *info = -4; } else if (*k < 0 || *k > nq) { *info = -5; } else if (*lda < max(1,nq)) { *info = -7; } else if (*ldc < max(1,*m)) { *info = -10; } if (*info != 0) { i__1 = -(*info); xerbla_("DORM2L", &i__1); return 0; } /* Quick return if possible */ if (*m == 0 || *n == 0 || *k == 0) { return 0; } if (left && notran || ! left && ! notran) { i1 = 1; i2 = *k; i3 = 1; } else { i1 = *k; i2 = 1; i3 = -1; } if (left) { ni = *n; } else { mi = *m; } i__1 = i2; i__2 = i3; for (i__ = i1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { if (left) { /* H(i) is applied to C(1:m-k+i,1:n) */ mi = *m - *k + i__; } else { /* H(i) is applied to C(1:m,1:n-k+i) */ ni = *n - *k + i__; } /* Apply H(i) */ aii = a[nq - *k + i__ + i__ * a_dim1]; a[nq - *k + i__ + i__ * a_dim1] = 1.; dlarf_(side, &mi, &ni, &a[i__ * a_dim1 + 1], &c__1, &tau[i__], &c__[ c_offset], ldc, &work[1]); a[nq - *k + i__ + i__ * a_dim1] = aii; /* L10: */ } return 0; /* End of DORM2L */ } /* dorm2l_ */