#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int slarf_(char *side, integer *m, integer *n, real *v, integer *incv, real *tau, real *c__, integer *ldc, real *work ) { /* -- LAPACK auxiliary routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 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' ===================================================================== Parameter adjustments */ /* Table of constant values */ static real c_b4 = 1.f; static real c_b5 = 0.f; static integer c__1 = 1; /* 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 *); --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_ */