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142 lines
3.7 KiB
142 lines
3.7 KiB
#include "clapack.h" |
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/* Table of constant values */ |
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static doublereal c_b4 = 1.; |
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static doublereal c_b5 = 0.; |
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static integer c__1 = 1; |
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/* Subroutine */ int dlarf_(char *side, integer *m, integer *n, doublereal *v, |
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integer *incv, doublereal *tau, doublereal *c__, integer *ldc, |
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doublereal *work) |
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{ |
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/* System generated locals */ |
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integer c_dim1, c_offset; |
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doublereal d__1; |
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/* Local variables */ |
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extern /* Subroutine */ int dger_(integer *, integer *, doublereal *, |
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doublereal *, integer *, doublereal *, integer *, doublereal *, |
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integer *); |
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extern logical lsame_(char *, char *); |
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extern /* Subroutine */ int dgemv_(char *, integer *, integer *, |
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doublereal *, doublereal *, integer *, doublereal *, integer *, |
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doublereal *, doublereal *, integer *); |
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/* -- LAPACK auxiliary routine (version 3.1) -- */ |
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/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ |
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/* November 2006 */ |
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/* .. Scalar Arguments .. */ |
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/* .. */ |
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/* .. Array Arguments .. */ |
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/* .. */ |
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/* Purpose */ |
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/* ======= */ |
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/* DLARF applies a real elementary reflector H to a real m by n matrix */ |
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/* C, from either the left or the right. H is represented in the form */ |
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/* H = I - tau * v * v' */ |
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/* where tau is a real scalar and v is a real vector. */ |
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/* If tau = 0, then H is taken to be the unit matrix. */ |
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/* Arguments */ |
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/* ========= */ |
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/* SIDE (input) CHARACTER*1 */ |
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/* = 'L': form H * C */ |
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/* = 'R': form C * H */ |
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/* M (input) INTEGER */ |
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/* The number of rows of the matrix C. */ |
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/* N (input) INTEGER */ |
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/* The number of columns of the matrix C. */ |
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/* V (input) DOUBLE PRECISION array, dimension */ |
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/* (1 + (M-1)*abs(INCV)) if SIDE = 'L' */ |
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/* or (1 + (N-1)*abs(INCV)) if SIDE = 'R' */ |
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/* The vector v in the representation of H. V is not used if */ |
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/* TAU = 0. */ |
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/* INCV (input) INTEGER */ |
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/* The increment between elements of v. INCV <> 0. */ |
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/* TAU (input) DOUBLE PRECISION */ |
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/* The value tau in the representation of H. */ |
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/* C (input/output) DOUBLE PRECISION array, dimension (LDC,N) */ |
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/* On entry, the m by n matrix C. */ |
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/* On exit, C is overwritten by the matrix H * C if SIDE = 'L', */ |
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/* or C * H if SIDE = 'R'. */ |
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/* LDC (input) INTEGER */ |
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/* The leading dimension of the array C. LDC >= max(1,M). */ |
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/* WORK (workspace) DOUBLE PRECISION array, dimension */ |
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/* (N) if SIDE = 'L' */ |
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/* or (M) if SIDE = 'R' */ |
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/* ===================================================================== */ |
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/* .. Parameters .. */ |
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/* .. */ |
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/* .. External Subroutines .. */ |
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/* .. */ |
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/* .. External Functions .. */ |
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/* .. */ |
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/* .. Executable Statements .. */ |
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/* Parameter adjustments */ |
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--v; |
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c_dim1 = *ldc; |
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c_offset = 1 + c_dim1; |
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c__ -= c_offset; |
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--work; |
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/* Function Body */ |
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if (lsame_(side, "L")) { |
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/* Form H * C */ |
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if (*tau != 0.) { |
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/* w := C' * v */ |
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dgemv_("Transpose", m, n, &c_b4, &c__[c_offset], ldc, &v[1], incv, |
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&c_b5, &work[1], &c__1); |
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/* C := C - v * w' */ |
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d__1 = -(*tau); |
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dger_(m, n, &d__1, &v[1], incv, &work[1], &c__1, &c__[c_offset], |
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ldc); |
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} |
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} else { |
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/* Form C * H */ |
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if (*tau != 0.) { |
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/* w := C * v */ |
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dgemv_("No transpose", m, n, &c_b4, &c__[c_offset], ldc, &v[1], |
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incv, &c_b5, &work[1], &c__1); |
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/* C := C - w * v' */ |
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d__1 = -(*tau); |
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dger_(m, n, &d__1, &work[1], &c__1, &v[1], incv, &c__[c_offset], |
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ldc); |
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} |
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} |
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return 0; |
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/* End of DLARF */ |
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} /* dlarf_ */
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