?labad

Returns the square root of the underflow and overflow thresholds if the exponent-range is very large.

Syntax

call slabad( small, large )

call dlabad( small, large )

Include Files

The FORTRAN 77 interfaces are specified in the mkl_lapack.fi include file (to be used in Fortran programs) and in the mkl_lapack.h include file (to be used in C programs).

Description

The routine takes as input the values computed by slamch/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 ?lamch. This subroutine is needed because ?lamch does not compensate for poor arithmetic in the upper half of the exponent range, as is found on a Cray.

Input Parameters

small

REAL for slabad

DOUBLE PRECISION for dlabad.

The underflow threshold as computed by ?lamch.

large

REAL for slabad

DOUBLE PRECISION for dlabad.

The overflow threshold as computed by ?lamch.

Output Parameters

small: On exit, if log10(large) is sufficiently large, the square root of small, otherwise unchanged.
large: On exit, if log10(large) is sufficiently large, the square root of large, otherwise unchanged.