#############################################################
# Output from 'meps' on Cray J90 (Cray 64-bit floating point)
#############################################################

#############################################################
# First consider source code:  Only difference between this 
# version and the SGI version is that here we use 'e0' 
# rather than 'd0' for real*8 constants.  A double precision
# variable or constant (d0) on a Cray system uses 16 bytes
# and arithmetic involving such quantities is *not* 
# implemented in hardware, and consequently is very slow 
# compared to real*8 (e0) arithmetic.
#############################################################

charon% more meps.f
c-----------------------------------------------------------
c     Computes and reports estimate of machine epsilon.
c
c     Recall: machine epsilon is smallest positive 'eps' 
c     such that 
c
c             (1.0e0 + eps ) .ne. (1.0e0)
c
c     Program accepts optional argument which specifies 
c     division factor: values close to 1.0 will result 
c     in more accurate estimate of machine epsilon.
c-----------------------------------------------------------
      program         meps

      implicit        none

      real            r8arg

      real            default_fac
      parameter     ( default_fac = 2.0e0 )

      real            eps,         neweps,        fac

      fac = r8arg(1,default_fac)
      write(0,*) 'meps: using division factor: ', fac

      eps    = 1.0e0
      neweps = 1.0e0
100   continue
         if( 1.0e0 .eq. (1.0e0 + neweps) ) then
            write(*,*) eps
            stop
         else
            eps    = neweps
            neweps = neweps / fac
         end if
      go to 100
200   continue

      stop

      end

charon% meps
 meps: using division factor: 2.
 7.105427357601001E-15
 STOP executed at line 38 in Fortran routine 'MEPS'
 CP: 0.004s,  Wallclock: 0.021s,  3.7% of 5-CPU Machine
 HWM mem: 147314, HWM stack: 2048, Stack overflows: 0

charon% meps 1.01
 meps: using division factor: 1.009999999999998
 7.10922461021392E-15
 STOP executed at line 38 in Fortran routine 'MEPS'
 CP: 0.008s,  Wallclock: 0.019s,  8.0% of 5-CPU Machine
 HWM mem: 147316, HWM stack: 2048, Stack overflows: 0

charon% meps 1.0001
 meps: using division factor: 1.000100000000003
 7.105756717509093E-15
 STOP executed at line 38 in Fortran routine 'MEPS'
 CP: 0.324s,  Wallclock: 0.331s,  19.6% of 5-CPU Machine
 HWM mem: 147316, HWM stack: 2048, Stack overflows: 0