#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int slabad_(real *small, real *large) { /* -- LAPACK auxiliary routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 Purpose ======= SLABAD takes as input the values computed by SLAMCH 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 SLAMCH. This subroutine is needed because SLAMCH does not compensate for poor arithmetic in the upper half of the exponent range, as is found on a Cray. Arguments ========= SMALL (input/output) REAL On entry, the underflow threshold as computed by SLAMCH. On exit, if LOG10(LARGE) is sufficiently large, the square root of SMALL, otherwise unchanged. LARGE (input/output) REAL On entry, the overflow threshold as computed by SLAMCH. On exit, if LOG10(LARGE) is sufficiently large, the square root of LARGE, otherwise unchanged. ===================================================================== If it looks like we're on a Cray, take the square root of SMALL and LARGE to avoid overflow and underflow problems. */ /* Builtin functions */ double r_lg10(real *), sqrt(doublereal); if (r_lg10(large) > 2e3f) { *small = sqrt(*small); *large = sqrt(*large); } return 0; /* End of SLABAD */ } /* slabad_ */