HP MLIB User's Guide Vol. 2 7th Ed.

656 HP MLIB LAPACK User’s Guide

SLAMCH/DLAMCH Return machine-dependent parameters

Output value The value of the requested machine-dependent

parameter.

Notes Actual character arguments in a subroutine call may be longer than the

corresponding dummy arguments. Therefore, readability of the function

reference may be improved by coding, for example, the name argument as ’Eps’

for ’E’ or ’Safemin’ for ’S’.

name = ’E’ or ’e’ eps The relative machine precision: the

smallest number ε such that 1 + ε can

be represented as a ﬂoating-point

number with 1 + ε >1.

name = ’S’ or ’s’ sfmin The safe minimum: the smallest

number such that 1/sfmin does not

overﬂow.

name = ’B’ or ’b’ base The base of the machine.

name = ’P’ or ’p’ prec eps×base.

name = ’N’ or ’n’ t The number of base-2 digits in the

mantissa.

name = ’R’ or ’r’ rnd 1.0 on machines where rounding

occurs on addition; zero otherwise.

name = ’M’ or ’m’ emin The smallest exponent before

underﬂow.

name = ’U’ or ’u’ rmin

The underﬂow threshold: base

emin−1

name = ’L’ or ’l’ emax The largest exponent before overﬂow.

name = ’O’ or ’o’ rmax The overﬂow threshold:

base

emax

×(1 −ε).