问Fortran:带实数类型参数的do循环

EN

ian-standard@barleybarber ~
$ cat inc.f90
Program inc

  Implicit None

  Real :: a
  Real :: a_lo, a_hi
  Real :: da

  Integer :: n_points
  Integer :: i

  Write( *, * ) 'a hi?'
  Read ( *, * )  a_hi
  Write( *, * ) 'a lo?'
  Read ( *, * )  a_lo
  Write( *, * ) 'da?'
  Read ( *, * )  da

  n_points = Int( ( a_hi - a_lo ) / da )

  ! First way - parallelisable
  Write( *, * ) 'First way'
  Do i = 0, n_points
     a = a_lo + Real( i ) * da
     Write( *, * ) a
  End Do

  ! Second way - not parallelisable
  Write( *, * ) 'Second way'
  a = a_lo
  Do While( a <= a_hi )
     Write( *, * ) a
     a = a + da
  End Do


End Program inc

ian-standard@barleybarber ~
$ gfortran -std=f2003 -Wall -Wextra -fcheck=all -O -g inc.f90 -o inc

ian-standard@barleybarber ~
$ ./inc
 a hi?
1
 a lo?
0
 da?
0.1
 First way
   0.00000000
  0.100000001
  0.200000003
  0.300000012
  0.400000006
  0.500000000
  0.600000024
  0.699999988
  0.800000012
  0.900000036
   1.00000000
 Second way
   0.00000000
  0.100000001
  0.200000003
  0.300000012
  0.400000006
  0.500000000
  0.600000024
  0.700000048
  0.800000072
  0.900000095