bug?

[root]

Dear Sir/Madam,

This very simple FORTRAN codes does not compile.
What is the problem? The error message is below

CODE:
       program teste
      implicit none
      real*8 q
      parameter (q=4.d0*datan(1.d0))
      print*, q
      end


COMPILER ERROR MESSAGE:


[root@borboleta nuno]# g77 teste.f
teste.f: In program `teste':
teste.f:4:
         parameter (q=4.d0*datan(1.d0))
                           ^
Invalid declaration of or reference to symbol `datan' at (^) [initially
seen at (^)]
[root@borboleta nuno]#

------------------------------------------------------------------
If I write the code has follows it compiles, but I still get a strange
message. (see below)

CODE:
      program teste
      implicit none
      real*8 q
      q=4.d0*datan(1.d0)
      print*, q
      end


COMPILER  MESSAGE:
root@borboleta nuno]# g77 teste.f
/usr/lib/gcc-lib/i386-redhat-linux/2.96/libg2c.a(open.o): In function
`f_open':
open.o(.text+0x4e6): the use of `tempnam' is dangerous, better use
`mkstemp'
--------------------------------------------------------------------
If I use the fort77 compiler I have no problem at all.

Could you please help?

Sincerely,

Nuno Peres