123 SUBROUTINE slarf( SIDE, M, N, V, INCV, TAU, C, LDC, WORK )
131 INTEGER INCV, LDC, M, N
135 REAL C( LDC, * ), V( * ), WORK( * )
142 parameter( one = 1.0e+0, zero = 0.0e+0 )
146 INTEGER I, LASTV, LASTC
153 INTEGER ILASLR, ILASLC
154 EXTERNAL lsame, ilaslr, ilaslc
158 applyleft = lsame( side,
'L' )
161 IF( tau.NE.zero )
THEN
170 i = 1 + (lastv-1) * incv
175 DO WHILE( lastv.GT.0 .AND. v( i ).EQ.zero )
181 lastc = ilaslc(lastv, n, c, ldc)
184 lastc = ilaslr(m, lastv, c, ldc)
193 IF( lastv.GT.0 )
THEN
197 CALL sgemv(
'Transpose', lastv, lastc, one, c, ldc, v, incv,
202 CALL sger( lastv, lastc, -tau, v, incv, work, 1, c, ldc )
208 IF( lastv.GT.0 )
THEN
212 CALL sgemv(
'No transpose', lastc, lastv, one, c, ldc,
213 $ v, incv, zero, work, 1 )
217 CALL sger( lastc, lastv, -tau, work, 1, v, incv, c, ldc )
subroutine slarf(SIDE, M, N, V, INCV, TAU, C, LDC, WORK)
SLARF applies an elementary reflector to a general rectangular matrix.
subroutine sger(M, N, ALPHA, X, INCX, Y, INCY, A, LDA)
SGER
subroutine sgemv(TRANS, M, N, ALPHA, A, LDA, X, INCX, BETA, Y, INCY)
SGEMV