#include "clapack.h" /* Table of constant values */ static real c_b4 = 1.f; static real c_b5 = 0.f; static integer c__1 = 1; /* Subroutine */ int slarf_(char *side, integer *m, integer *n, real *v, integer *incv, real *tau, real *c__, integer *ldc, real *work) { /* System generated locals */ integer c_dim1, c_offset; real r__1; /* Local variables */ extern /* Subroutine */ int sger_(integer *, integer *, real *, real *, integer *, real *, integer *, real *, integer *); extern logical lsame_(char *, char *); extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *, real *, integer *, real *, integer *, real *, real *, integer *); /* -- LAPACK auxiliary routine (version 3.1) -- */ /* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ /* November 2006 */ /* .. Scalar Arguments .. */ /* .. */ /* .. Array Arguments .. */ /* .. */ /* Purpose */ /* ======= */ /* SLARF applies a real elementary reflector H to a real m by n matrix */ /* C, from either the left or the right. H is represented in the form */ /* H = I - tau * v * v' */ /* where tau is a real scalar and v is a real vector. */ /* If tau = 0, then H is taken to be the unit matrix. */ /* Arguments */ /* ========= */ /* SIDE (input) CHARACTER*1 */ /* = 'L': form H * C */ /* = 'R': form C * H */ /* M (input) INTEGER */ /* The number of rows of the matrix C. */ /* N (input) INTEGER */ /* The number of columns of the matrix C. */ /* V (input) REAL array, dimension */ /* (1 + (M-1)*abs(INCV)) if SIDE = 'L' */ /* or (1 + (N-1)*abs(INCV)) if SIDE = 'R' */ /* The vector v in the representation of H. V is not used if */ /* TAU = 0. */ /* INCV (input) INTEGER */ /* The increment between elements of v. INCV <> 0. */ /* TAU (input) REAL */ /* The value tau in the representation of H. */ /* C (input/output) REAL array, dimension (LDC,N) */ /* On entry, the m by n matrix C. */ /* On exit, C is overwritten by the matrix H * C if SIDE = 'L', */ /* or C * H if SIDE = 'R'. */ /* LDC (input) INTEGER */ /* The leading dimension of the array C. LDC >= max(1,M). */ /* WORK (workspace) REAL array, dimension */ /* (N) if SIDE = 'L' */ /* or (M) if SIDE = 'R' */ /* ===================================================================== */ /* .. Parameters .. */ /* .. */ /* .. External Subroutines .. */ /* .. */ /* .. External Functions .. */ /* .. */ /* .. Executable Statements .. */ /* Parameter adjustments */ --v; c_dim1 = *ldc; c_offset = 1 + c_dim1; c__ -= c_offset; --work; /* Function Body */ if (lsame_(side, "L")) { /* Form H * C */ if (*tau != 0.f) { /* w := C' * v */ sgemv_("Transpose", m, n, &c_b4, &c__[c_offset], ldc, &v[1], incv, &c_b5, &work[1], &c__1); /* C := C - v * w' */ r__1 = -(*tau); sger_(m, n, &r__1, &v[1], incv, &work[1], &c__1, &c__[c_offset], ldc); } } else { /* Form C * H */ if (*tau != 0.f) { /* w := C * v */ sgemv_("No transpose", m, n, &c_b4, &c__[c_offset], ldc, &v[1], incv, &c_b5, &work[1], &c__1); /* C := C - w * v' */ r__1 = -(*tau); sger_(m, n, &r__1, &work[1], &c__1, &v[1], incv, &c__[c_offset], ldc); } } return 0; /* End of SLARF */ } /* slarf_ */