learning functions

[RadSurfer <RadSurfer at yahoo dot com>]

Error messages I get are found below.
I need to learn how to do Functions (and Subroutines) in Fortran.
I am compiling this as .f95

I do not understand why I am getting so many errors,
nothing I do seems to reduce them; only increase them! 

I. In the first function JDtoMDY(JD,M,D,Y), JD is input value, and
M,D,Y is the only output:
1) in this function M,D,Y are written to, to create the needed result.
   month/day/year.
   

II. In the second function MDYtoJD(M,D,Y,JD) M,D,Y are input values only, and
JD is the only output:
1) am I permitted to set both JD and JDtoMDY to the same numerical value?
   this would be convenient.


in I.  M,D,Y are used for output; JD for input
in II. M,D,Y are purely input; JD for output
and should pose no problems for Fortran as these conditions are in
different functions, and thus do not conflict since only one function
can be called at a time.

I would just like to see this compile! I'm sure the declarations inside the
functions are at fault.

! Sat 01 Sep 2007 09:11:37 PM EDT 
! Convert to/from Gregorian/Julian Dates
! jgreg.f95

program jgreg
IMPLICIT NONE

Real(8) JD, M, D, Y
Integer n,c
Character arg*80,astr*45,buffer*256

   n = iargc()

   if (n == 1) then
      call getarg(1, arg);
      read(arg,*) JD  ! Get CmdLine value (Real8)
!     write(*,*) 'Fraction ',Fraction(JD);
   ! JDtoMDY(M,D,Y)
  else
      if (n == 3) then
         call getarg(1, arg);
         read(arg,*) M  ! Get CmdLine value (Real8)
         call getarg(2, arg);
         read(arg,*) D  ! Get CmdLine value (Real8)
         call getarg(3, arg);
         read(arg,*) Y  ! Get CmdLine value (Real8)
       ! JD = MDYtoJD(M,D,Y)
       else
          write(*,*) 'Error: Improper Number of Aruments!'
       end if
  end if

contains

function fix(x)
implicit none
real :: fix
real,intent(in) x
   if (x .lt. 0.0_8) then
      fix = ceil(x)
   else
      fix = floor(x)
   end if
function end fix

function JDtoMDY(JD,M,D,Y)
implicit none
real(8)       JDtoMDY 
intent(in)      JD    
intent(in out) M,D,Y  
! no code yet
function end JDtoMDY

function MDYtoJD(M,D,Y,JD)
implicit none
real(8)       MDYtoJD 
intent(in)     M,D,Y  
intent(in out)  JD    
  if (M<3.0) then 
      Y=Y-1; M=M+12.0;
  end if 

  JD = fix(Y/100.0)

  JD = ( 2.0 - JD + fix(JD/4.0))  + fix(365.25*Y)

     + fix(30.6001*(M+1.0)) + D + 1720994.5

  MDYtoJD = JD
function end MDYtoJD

end program jgreg

[RadSurfer@centos fortran]$ gfortran jg0.f95
jg0.f95:38.5:

real,intent(in) x
    1
Error: Invalid character in name at (1)
jg0.f95:44:

function end fix
1
Error: Unclassifiable statement at (1)
jg0.f95:46:

function JDtoMDY(JD,M,D,Y)
1
Error: Unclassifiable statement at (1)
jg0.f95:47.13:

implicit none
            1
Error: Unexpected IMPLICIT NONE statement at (1)
jg0.f95:48.22:

real(8)       JDtoMDY 
                     1
Error: Unexpected data declaration statement at (1)
jg0.f95:49.22:

intent(in)      JD    
                     1
Error: Unexpected attribute declaration statement at (1)
jg0.f95:50.22:

intent(in out) M,D,Y  
                     1
Error: Unexpected attribute declaration statement at (1)
jg0.f95:52:

function end JDtoMDY
1
Error: Unclassifiable statement at (1)
jg0.f95:54:

function MDYtoJD(M,D,Y,JD)
1
Error: Unclassifiable statement at (1)
jg0.f95:55.13:

implicit none
            1
Error: Unexpected IMPLICIT NONE statement at (1)
jg0.f95:56.22:

real(8)       MDYtoJD 
                     1
Error: Unexpected data declaration statement at (1)
jg0.f95:57.22:

intent(in)     M,D,Y  
                     1
Error: Unexpected attribute declaration statement at (1)
jg0.f95:58.22:

intent(in out)  JD    
                     1
Error: Unexpected attribute declaration statement at (1)
jg0.f95:62.2:

  JD = fix(Y/100.0)
 1
Error: Unclassifiable statement at (1)
jg0.f95:63.23:

  JD = ( 2.0 - JD + fix(JD/4.0))  + fix(365.25*Y)
                      1
Error: Expected a right parenthesis in expression at (1)
jg0.f95:64.6:

     + fix(30.6001*(M+1.0)) + D + 1720994.5
     1
Error: Invalid character in name at (1)
jg0.f95:66:

function end MDYtoJD
1
Error: Unclassifiable statement at (1)
jg0.f95:68.3:

end program jgreg
  1
Error: Expecting END FUNCTION statement at (1)
Error: Unexpected end of file in 'jg0.f95'
[RadSurfer@centos fortran]$