On Tue, 26 Mar 2002, Silvio a Beccara wrote:

Hello,

thank you for your help; under which version have you tried compiling this, and under which OS?

[pal06] bohnen $ gpc -v Reading specs from /afs/desy.de/user/b/bohnen/.gnu/lib/gcc-lib/i386-suse-linux/2.95.2/specs gpc version 20020304, based on 2.95.2 19991024 (release)

[pal06] bohnen $ uname -a Linux pal06 2.4.18 #1 SMP Tue Mar 5 15:27:45 MET 2002 i686 unknown

AFAIK any floating point unit can be configured to treat 'out of range' FP-numbers (NaNs) as legal infinity/zero values or as errors. I couldn't find any hint about 'NaN' or 'IEEE' in the gpc - units directory to control this behavior. If there is no user control on that, the current behavior of gpc seems to me the best solution. Otherwise one might run into severe mathematical problems without any notification.

Ernst-Ludwig

Regards

Silvio

...

Hello, I changed your program somewhat:

PROGRAM espa; var i, j, k : integer; esp, res : double;

begin writeln (exp(1.0));

^^^^^^^^^^^^^^^^^^^ this is garbage, I forgot the value of e

...

for i := 1 to 50000 do begin esp := i * 0.1 ; res := exp ( -esp ); writeln (' Minus the exponential of ', esp :5 :1, ' is ', res ); end end.

Last lines written are: ...... Minus the exponential of 744.9 is 4.940656458412465e-324 Minus the exponential of 745.0 is 4.940656458412465e-324 Minus the exponential of 745.1 is 4.940656458412465e-324 espa: error in exponentiation (Numerical result out of range) (error #700 at 8049c8a)

This indicates that res runs into undefined range between zero and minimum valid value of IEEE double precision numbers. Minimum decimal value is approximately +/- 10**(-323). If your application allows lower values to be interpreted as zero (0.0) you may tell it to gpc, but I don't know how to do that..

Ernst-Ludwig

On Tue, 26 Mar 2002, Silvio a Beccara wrote:

...

Hello,

I tried compiling this simple program, with GPC RC3 (20020304), with GCC 2.95.3 (20010315).

program espa;

var

i, j, k: integer;

esp: double;

res: double;

begin

for i := 1 to 50 do begin

esp := i * 1000 ;

res := exp ( -esp );

writeln (' Minus the exponential of ', esp :1 :0, ' is ', res :1 :15 );

end;

end.

Surprisingly, and disappointingly, when I run it I get the following result:

espa: error in exponentiation (Numerical result out of range) (error #700 at 8049c75)

while with any Pascal (like FPC), and C compiler, I get no error (like it should be ). It really looks like a bug.

Can anyone help?

Thanks, regards

Silvio a Beccara