dlamch.f - Man Page

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

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..

Parameters

A

          A is a DOUBLE PRECISION

B

          B is a DOUBLE PRECISION
          The values A and B.

Definition at line 171 of file dlamch.f.

DLAMCH

Purpose:

 DLAMCH determines double precision machine parameters.

Parameters

CMACH

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

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 68 of file dlamch.f.