[Lazarus] exception handling

[Andrea Mauri]

Dear all,
I developed an application that perform some calculations.
This application has a gui version and a console version, it runs on 
windows and linux.
Both apps use the same units for calculation, only the interface units 
are different.
I have some problems in the exception handling.
Some calculations include ln operations.
The calculations are under try except.

Sometimes happens that the argument (a) of b:= ln(a) is negative.
The gui app handles this operation giving as result b = NaN or Inf and 
it does not raise any exception while the concole app raise an 
exception: External SIGFPE.

How can I obtain the same behaviour on my app both on GUI and console? 
Which options I have to check?

Regards,
Andrea