编辑代码

program main
implicit none
  real :: a
  real :: b = 3.0
  real,parameter :: e = 0.0001

  a=sqrt(b)**2-b

  if( abs(a-0.0)<=e ) then
    write(*,*) "a等于0"
  else
    write(*,*) "a不等于0"
  end if

  stop
end