Math library not generating errno values or SIGFPE on Intel!!

Question

Hello. I posted this a long while back and got no responses, so I decided to ask again. I am writing a calculator, and it is not very nice for testing if I have to wind up with this:
<pre style="width: 600px; background-color: #F0F0F0">$ hoc
sqrt(-4)
nan
atan2(0,0)
0
pow(-4, 1/2)
nan
1e4000 * 1e4000
inf
(-1e4000) * (1e40000)
-inf
1e-40000
0
</pre>
My program handles SIGFPE and there is a function errcheck() that checks the value of errno. It seems like the atan2(), pow(), and sqrt() functions do not assign to errno like they should. I'm running on an Intel Mac, and it makes making sure this calculator works right a big pain. Does anyone PLEASE know how to fix this? THANKS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Answer 1

What x-bc does is: convert long function names (sin(), ...) to the short ones (s(), ...), save the final result in a temporary file, and just pipe bc -lq (include math library, no GNU bc banner) redirecting standard input to that temporary file over to their GTK+ text box. There's something that has to do with GNU bc then, and that results in a weird value (1) in my testing...
PS - The file is src/main_window.cc; function int main_window::executeBc() - on version 2.0: lines 376 through 408. The code that does converting long to short is unknown to me.
Message was edited by: andlabs
Message was edited by: andlabs