dlamch.f File Reference

Functions/Subroutines
double precision function	dlamch (cmach)
	DLAMCH
double precision function	dlamc3 (a, b)
	DLAMC3

Function/Subroutine Documentation

dlamc3()

double precision function dlamc3	(	double precision	a,
		double precision	b
	)

DLAMC3

Purpose:

 DLAMC3  is intended to force  A  and  B  to be stored prior to doing
 the addition of  A  and  B ,  for use in situations where optimizers
 might hold one of these in a register.

Author

LAPACK is a software package provided by Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..

Date

November 2011

Parameters

[in]	A	A is a DOUBLE PRECISION
[in]	B	B is a DOUBLE PRECISION The values A and B.

dlamch()

double precision function dlamch

(

character

cmach

)

DLAMCH

Purpose:

 DLAMCH determines double precision machine parameters.

Parameters

[in]

CMACH

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

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date

November 2011