DragonFly On-Line Manual Pages

Search: Section:  

PDLAMCH(l)                             )                            PDLAMCH(l)


NAME

       PDLAMCH - determine double precision machine parameters


SYNOPSIS

       DOUBLE PRECISION FUNCTION PDLAMCH( ICTXT, CMACH )
           CHARACTER CMACH
           INTEGER ICTXT


PURPOSE

       PDLAMCH determines double precision machine parameters.


ARGUMENTS

       ICTXT   (global input) INTEGER
               The BLACS context handle in which the computation takes place.

       CMACH   (global input) CHARACTER*1
               Specifies the value to be returned by PDLAMCH:
               = 'E' or 'e',   PDLAMCH := eps
               = 'S' or 's ,   PDLAMCH := sfmin
               = 'B' or 'b',   PDLAMCH := base
               = 'P' or 'p',   PDLAMCH := eps*base
               = 'N' or 'n',   PDLAMCH := t
               = 'R' or 'r',   PDLAMCH := rnd
               = 'M' or 'm',   PDLAMCH := emin
               = 'U' or 'u',   PDLAMCH := rmin
               = 'L' or 'l',   PDLAMCH := emax
               = 'O' or 'o',   PDLAMCH := 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)

ScaLAPACK version 1.7           13 August 2001                      PDLAMCH(l)

Search: Section: