I encounter a strange difference in the behaviour of NaN values between windows 32 and 64 bit. Have a look at the following program:

-----------------------
program NanExample;
uses
  math;
var
  a, b, c: Double;
begin
  a := 0.0/0.0;
  b := 0.0/0.0;
  c := max(a,b);
  if IsNan(c) then
    WriteLn('NaN');
end.
-----------------------

On 32 bit this writes 'NaN' as expected. On 64 bit I get an SIGFPE exception on the max-function. Is there some specific compiler setting that I should be aware of to make this work on 64 bit?

Kind regards,
Birger Jansen

It should cause an exception everywhere by default (it does on PowerPC 32 bit). You have to use math.setexceptionmask if you want to mask exceptions for invalid floating point operations: http://www.freepascal.org/docs-html/rtl/math/setexceptionmask.html

Jonas

It should cause an exception everywhere by default (it does on PowerPC 32 bit). You have to use math.setexceptionmask if you want to mask exceptions for invalid floating point operations: http://www.freepascal.org/docs-html/rtl/math/setexceptionmask.html

Thanks, that fixed my problem. Strange though that the test program runs without problems on Win32 and in Delphi.

Kind regards,
Birger