dlamch(3)

NAME

DLAMCH - determine 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:
= 'E' or 'e', DLAMCH := eps
= 'S' or 's , DLAMCH := sfmin
= 'B' or 'b', DLAMCH := base
= 'P' or 'p', DLAMCH := eps*base
= 'N' or 'n', DLAMCH := t
= 'R' or 'r', DLAMCH := rnd
= 'M' or 'm', DLAMCH := emin
= 'U' or 'u', DLAMCH := rmin
= 'L' or 'l', DLAMCH := emax
= 'O' or 'o', 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 thresh

old - (base**emax)*(1-eps)

LAPACK version 3.0 15 June 2000

DLAMCH(3)