gfortran return values of type real(kind=8) or real(kind-10) are mangled

[Polyergic (Shad Sterling)]

The output should be one number twice and a second number twice. With kind=8 or kind=10, passing a value into the function works (the first number is repeated correctly), but returning a value out of the function does not (the second number is not repeated correctly).

output with kind=4:

   1.2345679    
   1.2345679    
  0.34567890    
  0.34567890    

output with kind=8:

   1.2345678806304932     
   1.2345678806304932     
  0.34567889571189880     
  3.68934881474191032E+019

output with kind=10:

   1.2345678806304931641      
   1.2345678806304931641      
  0.34567889571189880371      
 -3.74416264051907754506E-0013

code with kind=10:

program bugtest
real(kind=10) :: test = 1.234567890123456789012345678901
  print *, test
  test = check(test)
  print *, test
end program bugtest

function check(x)
real(kind=10) :: x, check
  check = 0.345678901234567890123456789012
  print *, x
  print *, check
end

environment:

$ system_profiler SPSoftwareDataType
Software:

    System Software Overview:

      System Version: Mac OS X 10.7.4 (11E53)
      Kernel Version: Darwin 11.4.0
      Boot Volume: Macintosh HD
      Boot Mode: Normal
      Computer Name: Shad Sterling’s MacBook
      User Name: Shad Sterling (polyergic)
      Secure Virtual Memory: Enabled
      64-bit Kernel and Extensions: No
      Time since boot: 5 days 13:13

$ port version
Version: 2.1.2
$ which gfortran
/opt/local/bin/gfortran
[2012-Sep-19-Wed 19:33:59] polyergic@laconic : ~/Documents/2012/MATH 4610 - Numerical Analysis 1/Homework 2 $ ls -l `which gfortran`
lrwxr-xr-x 1 root admin 30 Sep 19 12:05 /opt/local/bin/gfortran -> /opt/local/bin/gfortran-mp-4.5
[2012-Sep-19-Wed 19:34:18] polyergic@laconic : ~/Documents/2012/MATH 4610 - Numerical Analysis 1/Homework 2 $ gfortran --version
GNU Fortran (MacPorts gcc45 4.5.4_4) 4.5.4
Copyright (C) 2010 Free Software Foundation, Inc.

GNU Fortran comes with NO WARRANTY, to the extent permitted by law.
You may redistribute copies of GNU Fortran
under the terms of the GNU General Public License.
For more information about these matters, see the file named COPYING

(I don't understand the "64-bit Kernel and Extensions: No"; Activity Monitor shows mostly 64-bit processes, including every instance of bash.)

[Polyergic (Shad Sterling)]

I'm also getting a similar error with integers. I'm new to fortran, so maybe I'm missing something, but I haven't found anything that explains this.

output with integer:

           1
           1
          -1
           0

code with integer:

program bugtest2
integer :: test = 1
  print *, test
  test = check(test)
  print *, test
end program bugtest2

function check(x)
integer :: x, check
  check = -1
  print *, x
  print *, check
end

[Polyergic (Shad Sterling)]

Apparently I was missing an "IMPLICIT NONE" and type declarations for called functions at the top of every program/function/subroutine. If I ever write about Fortran I'll include that anywhere I describe types or calls (unlike any examples or tutorials I've seen). So this should be closed as invalid (I don't see a way to do that myself).