dlamch (l) - Linux Manuals

dlamch: double precision machine parameters

NAME

DLAMCH - double precision machine parameters

SYNOPSIS

DOUBLE PRECISION

FUNCTION DLAMCH( CMACH )

    

CHARACTER CMACH

PURPOSE

DLAMCH determines double precision machine parameters.

ARGUMENTS

CMACH (input) CHARACTER*1

Specifies the value to be returned by DLAMCH:
= aqEaq or aqeaq, DLAMCH := eps
= aqSaq or aqs , DLAMCH := sfmin
= aqBaq or aqbaq, DLAMCH := base
= aqPaq or aqpaq, DLAMCH := eps*base
= aqNaq or aqnaq, DLAMCH := t
= aqRaq or aqraq, DLAMCH := rnd
= aqMaq or aqmaq, DLAMCH := emin
= aqUaq or aquaq, DLAMCH := rmin
= aqLaq or aqlaq, DLAMCH := emax
= aqOaq or aqoaq, DLAMCH := 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)