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
|
/* dlabad.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"
#include "blaswrap.h"
/* Subroutine */ int dlabad_(doublereal *small, doublereal *large)
{
/* Builtin functions */
double d_lg10(doublereal *), sqrt(doublereal);
/* -- LAPACK auxiliary routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DLABAD takes as input the values computed by DLAMCH for underflow and */
/* overflow, and returns the square root of each of these values if the */
/* log of LARGE is sufficiently large. This subroutine is intended to */
/* identify machines with a large exponent range, such as the Crays, and */
/* redefine the underflow and overflow limits to be the square roots of */
/* the values computed by DLAMCH. This subroutine is needed because */
/* DLAMCH does not compensate for poor arithmetic in the upper half of */
/* the exponent range, as is found on a Cray. */
/* Arguments */
/* ========= */
/* SMALL (input/output) DOUBLE PRECISION */
/* On entry, the underflow threshold as computed by DLAMCH. */
/* On exit, if LOG10(LARGE) is sufficiently large, the square */
/* root of SMALL, otherwise unchanged. */
/* LARGE (input/output) DOUBLE PRECISION */
/* On entry, the overflow threshold as computed by DLAMCH. */
/* On exit, if LOG10(LARGE) is sufficiently large, the square */
/* root of LARGE, otherwise unchanged. */
/* ===================================================================== */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* If it looks like we're on a Cray, take the square root of */
/* SMALL and LARGE to avoid overflow and underflow problems. */
if (d_lg10(large) > 2e3) {
*small = sqrt(*small);
*large = sqrt(*large);
}
return 0;
/* End of DLABAD */
} /* dlabad_ */
|
