LAPACK 3.12.0 LAPACK: Linear Algebra PACKage
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sscal.f
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1*> \brief \b SSCAL
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8* Definition:
9* ===========
10*
11* SUBROUTINE SSCAL(N,SA,SX,INCX)
12*
13* .. Scalar Arguments ..
14* REAL SA
15* INTEGER INCX,N
16* ..
17* .. Array Arguments ..
18* REAL SX(*)
19* ..
20*
21*
22*> \par Purpose:
23* =============
24*>
25*> \verbatim
26*>
27*> SSCAL scales a vector by a constant.
28*> uses unrolled loops for increment equal to 1.
29*> \endverbatim
30*
31* Arguments:
32* ==========
33*
34*> \param[in] N
35*> \verbatim
36*> N is INTEGER
37*> number of elements in input vector(s)
38*> \endverbatim
39*>
40*> \param[in] SA
41*> \verbatim
42*> SA is REAL
43*> On entry, SA specifies the scalar alpha.
44*> \endverbatim
45*>
46*> \param[in,out] SX
47*> \verbatim
48*> SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
49*> \endverbatim
50*>
51*> \param[in] INCX
52*> \verbatim
53*> INCX is INTEGER
54*> storage spacing between elements of SX
55*> \endverbatim
56*
57* Authors:
58* ========
59*
60*> \author Univ. of Tennessee
61*> \author Univ. of California Berkeley
62*> \author Univ. of Colorado Denver
63*> \author NAG Ltd.
64*
65*> \ingroup scal
66*
67*> \par Further Details:
68* =====================
69*>
70*> \verbatim
71*>
72*> jack dongarra, linpack, 3/11/78.
73*> modified 3/93 to return if incx .le. 0.
74*> modified 12/3/93, array(1) declarations changed to array(*)
75*> \endverbatim
76*>
77* =====================================================================
78 SUBROUTINE sscal(N,SA,SX,INCX)
79*
80* -- Reference BLAS level1 routine --
81* -- Reference BLAS is a software package provided by Univ. of Tennessee, --
82* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
83*
84* .. Scalar Arguments ..
85 REAL SA
86 INTEGER INCX,N
87* ..
88* .. Array Arguments ..
89 REAL SX(*)
90* ..
91*
92* =====================================================================
93*
94* .. Local Scalars ..
95 INTEGER I,M,MP1,NINCX
96* ..
97* .. Parameters ..
98 REAL ONE
99 parameter(one=1.0e+0)
100* ..
101* .. Intrinsic Functions ..
102 INTRINSIC mod
103* ..
104 IF (n.LE.0 .OR. incx.LE.0 .OR. sa.EQ.one) RETURN
105 IF (incx.EQ.1) THEN
106*
107* code for increment equal to 1
108*
109*
110* clean-up loop
111*
112 m = mod(n,5)
113 IF (m.NE.0) THEN
114 DO i = 1,m
115 sx(i) = sa*sx(i)
116 END DO
117 IF (n.LT.5) RETURN
118 END IF
119 mp1 = m + 1
120 DO i = mp1,n,5
121 sx(i) = sa*sx(i)
122 sx(i+1) = sa*sx(i+1)
123 sx(i+2) = sa*sx(i+2)
124 sx(i+3) = sa*sx(i+3)
125 sx(i+4) = sa*sx(i+4)
126 END DO
127 ELSE
128*
129* code for increment not equal to 1
130*
131 nincx = n*incx
132 DO i = 1,nincx,incx
133 sx(i) = sa*sx(i)
134 END DO
135 END IF
136 RETURN
137*
138* End of SSCAL
139*
140 END
subroutine sscal(n, sa, sx, incx)
SSCAL
Definition sscal.f:79