!Complex.Java Fortran90 Conversion

!Module containing complex methods and type definitions
module complex_module  
  !Define complex type
  type public_complex
     real :: re, im
  end type public_complex

  !Add the functions for complex mathematics
  contains
    !Add two complex numbers
    function add(a,b)
      implicit none
      type (public_complex), intent(in) :: a,b
      type (public_complex) :: add
      add%re = a%re + b%re
      add%im = a%im + b%im
    end function add

    !Subtract b from a complex numbers
    function subtract(a,b)
      implicit none
      type (public_complex), intent(in) :: a,b
      type (public_complex) :: subtract
      subtract%re = a%re - b%re
      subtract%im = a%im - b%im
    end function subtract

    !Multiply two complex numbers
    function multiply(a,b)
      implicit none
      type (public_complex), intent(in) :: a,b
      type (public_complex) :: multiply
      multiply%re = a%re * b%re - a%im * b%im
      multiply%im = a%re * b%im + a%im * b%re
    end function multiply

    !Divide two complex numbers
    function divide(a,b)
      implicit none
      type (public_complex), intent(in) :: a,b
      type (public_complex) :: divide
      divide%re = (a%re * b%re + a%im * b%im)/(b%re**2 + b%im**2)
      divide%im = (a%im * b%re - a%re * b%im)/(b%re**2  + b%im**2)
    end function divide
end module complex_module

!Begin main program
program main_program
  use complex_module
  implicit none  
  type(public_complex) :: a,b,c
  character ch
  a%re=1.
  a%im=2.
  b%re=3.
  b%im=4.

  if(a%im>=0.0) then 
     ch = '+'
  else if(a%im<0.0) then 
     ch = '-'     
  end if
  write(*,*) 'a = ', a%re, ch, abs(a%im), 'i'

  if(b%im>=0.0) then 
     ch = '+'
  else if(b%im<0.0) then 
     ch = '-'     
  end if
  write(*,*) 'b = ', b%re, ch, abs(b%im), 'i'

  c = add(a,b)
  if(c%im>=0.0) then 
     ch = '+'
  else if(c%im<0.0) then 
     ch = '-'
  end if
  write(*,*) 'a + b = ', c%re, ch, abs(c%im),'i'

  c = subtract(a,b)
  if(c%im>=0.0) then 
     ch = '+'
  else if(c%im<0.0) then 
     ch = '-'     
  end if 
  write(*,*) 'a - b = ', c%re, ch, abs(c%im),'i'

  c = multiply(a,b)
  if(c%im>=0.0) then 
     ch = '+'
  else if(c%im<0.0) then 
     ch = '-'     
  end if
  write(*,*) 'a * b = ', c%re, ch, abs(c%im),'i'

  if(b%re==0. .AND. b%im==0.) then
     write(*,*) 'Error: division by zero ',b%re,'+',b%im,'i'
  else
     c = divide(a,b)
     if(c%im>=0.0) then 
        ch = '+'
     else if(c%im<0.0) then 
        ch = '-'     
     end if
     write(*,*) 'a / b = ', c%re, ch, abs(c%im),'i'
  end if
end program main_program