1*> \brief \b SRSCL multiplies a vector by the reciprocal of a real scalar.
2*
3*  =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6*            http://www.netlib.org/lapack/explore-html/
7*
8*> \htmlonly
9*> Download SRSCL + dependencies
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11*> [TGZ]</a>
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13*> [ZIP]</a>
14*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/srscl.f">
15*> [TXT]</a>
16*> \endhtmlonly
17*
18*  Definition:
19*  ===========
20*
21*       SUBROUTINE SRSCL( N, SA, SX, INCX )
22*
23*       .. Scalar Arguments ..
24*       INTEGER            INCX, N
25*       REAL               SA
26*       ..
27*       .. Array Arguments ..
28*       REAL               SX( * )
29*       ..
30*
31*
32*> \par Purpose:
33*  =============
34*>
35*> \verbatim
36*>
37*> SRSCL multiplies an n-element real vector x by the real scalar 1/a.
38*> This is done without overflow or underflow as long as
39*> the final result x/a does not overflow or underflow.
40*> \endverbatim
41*
42*  Arguments:
43*  ==========
44*
45*> \param[in] N
46*> \verbatim
47*>          N is INTEGER
48*>          The number of components of the vector x.
49*> \endverbatim
50*>
51*> \param[in] SA
52*> \verbatim
53*>          SA is REAL
54*>          The scalar a which is used to divide each component of x.
55*>          SA must be >= 0, or the subroutine will divide by zero.
56*> \endverbatim
57*>
58*> \param[in,out] SX
59*> \verbatim
60*>          SX is REAL array, dimension
61*>                         (1+(N-1)*abs(INCX))
62*>          The n-element vector x.
63*> \endverbatim
64*>
65*> \param[in] INCX
66*> \verbatim
67*>          INCX is INTEGER
68*>          The increment between successive values of the vector SX.
69*>          > 0:  SX(1) = X(1) and SX(1+(i-1)*INCX) = x(i),     1< i<= n
70*> \endverbatim
71*
72*  Authors:
73*  ========
74*
75*> \author Univ. of Tennessee
76*> \author Univ. of California Berkeley
77*> \author Univ. of Colorado Denver
78*> \author NAG Ltd.
79*
80*> \date December 2016
81*
82*> \ingroup realOTHERauxiliary
83*
84*  =====================================================================
85      SUBROUTINE SRSCL( N, SA, SX, INCX )
86*
87*  -- LAPACK auxiliary routine (version 3.7.0) --
88*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
89*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
90*     December 2016
91*
92*     .. Scalar Arguments ..
93      INTEGER            INCX, N
94      REAL               SA
95*     ..
96*     .. Array Arguments ..
97      REAL               SX( * )
98*     ..
99*
100* =====================================================================
101*
102*     .. Parameters ..
103      REAL               ONE, ZERO
104      PARAMETER          ( ONE = 1.0E+0, ZERO = 0.0E+0 )
105*     ..
106*     .. Local Scalars ..
107      LOGICAL            DONE
108      REAL               BIGNUM, CDEN, CDEN1, CNUM, CNUM1, MUL, SMLNUM
109*     ..
110*     .. External Functions ..
111      REAL               SLAMCH
112      EXTERNAL           SLAMCH
113*     ..
114*     .. External Subroutines ..
115      EXTERNAL           SLABAD, SSCAL
116*     ..
117*     .. Intrinsic Functions ..
118      INTRINSIC          ABS
119*     ..
120*     .. Executable Statements ..
121*
122*     Quick return if possible
123*
124      IF( N.LE.0 )
125     $   RETURN
126*
127*     Get machine parameters
128*
129      SMLNUM = SLAMCH( 'S' )
130      BIGNUM = ONE / SMLNUM
131      CALL SLABAD( SMLNUM, BIGNUM )
132*
133*     Initialize the denominator to SA and the numerator to 1.
134*
135      CDEN = SA
136      CNUM = ONE
137*
138   10 CONTINUE
139      CDEN1 = CDEN*SMLNUM
140      CNUM1 = CNUM / BIGNUM
141      IF( ABS( CDEN1 ).GT.ABS( CNUM ) .AND. CNUM.NE.ZERO ) THEN
142*
143*        Pre-multiply X by SMLNUM if CDEN is large compared to CNUM.
144*
145         MUL = SMLNUM
146         DONE = .FALSE.
147         CDEN = CDEN1
148      ELSE IF( ABS( CNUM1 ).GT.ABS( CDEN ) ) THEN
149*
150*        Pre-multiply X by BIGNUM if CDEN is small compared to CNUM.
151*
152         MUL = BIGNUM
153         DONE = .FALSE.
154         CNUM = CNUM1
155      ELSE
156*
157*        Multiply X by CNUM / CDEN and return.
158*
159         MUL = CNUM / CDEN
160         DONE = .TRUE.
161      END IF
162*
163*     Scale the vector X by MUL
164*
165      CALL SSCAL( N, MUL, SX, INCX )
166*
167      IF( .NOT.DONE )
168     $   GO TO 10
169*
170      RETURN
171*
172*     End of SRSCL
173*
174      END
175