1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
|
/* ../../../dependencies/lapack/src/drscl.f -- translated by f2c (version 20061008).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#include "f2c.h"
/* Subroutine */ int drscl_(integer *n, doublereal *sa, doublereal *sx,
integer *incx)
{
static doublereal mul, cden;
static logical done;
static doublereal cnum, cden1, cnum1;
extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *,
integer *), dlabad_(doublereal *, doublereal *);
extern doublereal dlamch_(char *, ftnlen);
static doublereal bignum, smlnum;
/* -- LAPACK auxiliary routine (version 3.0) -- */
/* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
/* Courant Institute, Argonne National Lab, and Rice University */
/* September 30, 1994 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DRSCL multiplies an n-element real vector x by the real scalar 1/a. */
/* This is done without overflow or underflow as long as */
/* the final result x/a does not overflow or underflow. */
/* Arguments */
/* ========= */
/* N (input) INTEGER */
/* The number of components of the vector x. */
/* SA (input) DOUBLE PRECISION */
/* The scalar a which is used to divide each component of x. */
/* SA must be >= 0, or the subroutine will divide by zero. */
/* SX (input/output) DOUBLE PRECISION array, dimension */
/* (1+(N-1)*abs(INCX)) */
/* The n-element vector x. */
/* INCX (input) INTEGER */
/* The increment between successive values of the vector SX. */
/* > 0: SX(1) = X(1) and SX(1+(i-1)*INCX) = x(i), 1< i<= n */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Quick return if possible */
/* Parameter adjustments */
--sx;
/* Function Body */
if (*n <= 0) {
return 0;
}
/* Get machine parameters */
smlnum = dlamch_("S", (ftnlen)1);
bignum = 1. / smlnum;
dlabad_(&smlnum, &bignum);
/* Initialize the denominator to SA and the numerator to 1. */
cden = *sa;
cnum = 1.;
L10:
cden1 = cden * smlnum;
cnum1 = cnum / bignum;
if (abs(cden1) > abs(cnum) && cnum != 0.) {
/* Pre-multiply X by SMLNUM if CDEN is large compared to CNUM. */
mul = smlnum;
done = FALSE_;
cden = cden1;
} else if (abs(cnum1) > abs(cden)) {
/* Pre-multiply X by BIGNUM if CDEN is small compared to CNUM. */
mul = bignum;
done = FALSE_;
cnum = cnum1;
} else {
/* Multiply X by CNUM / CDEN and return. */
mul = cnum / cden;
done = TRUE_;
}
/* Scale the vector X by MUL */
dscal_(n, &mul, &sx[1], incx);
if (! done) {
goto L10;
}
return 0;
/* End of DRSCL */
} /* drscl_ */
|
