00001 /* slabad.f -- translated by f2c (version 20061008). 00002 You must link the resulting object file with libf2c: 00003 on Microsoft Windows system, link with libf2c.lib; 00004 on Linux or Unix systems, link with .../path/to/libf2c.a -lm 00005 or, if you install libf2c.a in a standard place, with -lf2c -lm 00006 -- in that order, at the end of the command line, as in 00007 cc *.o -lf2c -lm 00008 Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., 00009 00010 http://www.netlib.org/f2c/libf2c.zip 00011 */ 00012 00013 #include "f2c.h" 00014 #include "blaswrap.h" 00015 00016 /* Subroutine */ int slabad_(real *small, real *large) 00017 { 00018 /* Builtin functions */ 00019 double r_lg10(real *), sqrt(doublereal); 00020 00021 00022 /* -- LAPACK auxiliary routine (version 3.2) -- */ 00023 /* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ 00024 /* November 2006 */ 00025 00026 /* .. Scalar Arguments .. */ 00027 /* .. */ 00028 00029 /* Purpose */ 00030 /* ======= */ 00031 00032 /* SLABAD takes as input the values computed by SLAMCH for underflow and */ 00033 /* overflow, and returns the square root of each of these values if the */ 00034 /* log of LARGE is sufficiently large. This subroutine is intended to */ 00035 /* identify machines with a large exponent range, such as the Crays, and */ 00036 /* redefine the underflow and overflow limits to be the square roots of */ 00037 /* the values computed by SLAMCH. This subroutine is needed because */ 00038 /* SLAMCH does not compensate for poor arithmetic in the upper half of */ 00039 /* the exponent range, as is found on a Cray. */ 00040 00041 /* Arguments */ 00042 /* ========= */ 00043 00044 /* SMALL (input/output) REAL */ 00045 /* On entry, the underflow threshold as computed by SLAMCH. */ 00046 /* On exit, if LOG10(LARGE) is sufficiently large, the square */ 00047 /* root of SMALL, otherwise unchanged. */ 00048 00049 /* LARGE (input/output) REAL */ 00050 /* On entry, the overflow threshold as computed by SLAMCH. */ 00051 /* On exit, if LOG10(LARGE) is sufficiently large, the square */ 00052 /* root of LARGE, otherwise unchanged. */ 00053 00054 /* ===================================================================== */ 00055 00056 /* .. Intrinsic Functions .. */ 00057 /* .. */ 00058 /* .. Executable Statements .. */ 00059 00060 /* If it looks like we're on a Cray, take the square root of */ 00061 /* SMALL and LARGE to avoid overflow and underflow problems. */ 00062 00063 if (r_lg10(large) > 2e3f) { 00064 *small = sqrt(*small); 00065 *large = sqrt(*large); 00066 } 00067 00068 return 0; 00069 00070 /* End of SLABAD */ 00071 00072 } /* slabad_ */