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MathGroup Archive 2005

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FortranForm of Integers and Reals

  • To: mathgroup at smc.vnet.net
  • Subject: [mg60996] FortranForm of Integers and Reals
  • From: Robert Schoefbeck <schoefbeck at hep.itp.tuwien.ac.at>
  • Date: Fri, 7 Oct 2005 03:37:41 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Hello all,

I have a stupid problem when I try to export Fortran Code from 
Mathematica into some .F file.

For example, I want to achieve that

Format[3xy, FormatType->FortranForm]

gives

3d0*x*y

and that

Format[3. xy, FormatType->FortranForm]

should give

3.d0*x*y

That is, I want to have Integers as xdn and reals as ydn where n is the 
exponent of 10. First I tried

Unprotect[FortranForm];
FortranForm[int_Integer]:=DisplayForm[SequenceForm[int,d0]]
FortranForm[r_Real]:=
   NumberForm[r,16,ExponentFunction\[Rule]Identity,
     NumberFormat\[Rule](#1<>"d"<>#3&)]
Protect[FortranForm];

which gets me

FortranForm[1543254233.]
1.543254233d9

FortranForm[1]
1d0

which is JUST what I want, except that it doesnt work with ToString:

ToString[1543254233.,FormatType\[Rule]FortranForm]
1.543254233e9

ToString[1,FormatType\[Rule]FortranForm]
1

ToString[1.,FormatType\[Rule]FortranForm]
1.


The reason is that toString does not get the actual function FortranForm 
but only the Identifier "FortranForm" and then proceeds as usual, i.e. 
not as I want it to.


I have not succeded in redefining Format[int_, FortranForm] without 
generating infinite recursions.


I do think that there should be an easy way out.
I'd very much appreciate any help.

Robert Schoefbeck





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