?lamch

Syntax

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 function ?lamch determines single precision and double precision machine parameters.

Input Parameters

cmach

CHARACTER*1. Specifies the value to be returned by ?lamch:

= 'E' or 'e', val = eps

= 'S' or 's, val = sfmin

= 'B' or 'b', val = base

= 'P' or 'p', val = eps*base

= 'n' or 'n', val = t

= 'R' or 'r', val = rnd

= 'm' or 'm', val = emin

= 'U' or 'u', val = rmin

= 'L' or 'l', val = emax

= 'O' or 'o', val = rmax

where

eps = relative machine precision;

sfmin = safe minimum, such that 1/sfmin does not overflow;

base = base of the machine;

prec = eps*base;

t = number of (base) digits in the mantissa;

rnd = 1.0 when rounding occurs in addition, 0.0 otherwise;

emin = minimum exponent before (gradual) underflow;

rmin = underflow_threshold - base**(emin-1);

emax = largest exponent before overflow;

rmax = overflow_threshold - (base**emax)*(1-eps).

Output Parameters

val

REAL for slamch

DOUBLE PRECISION for dlamch

Value returned by the function.