Question about Perl "exp" function? Please help!

[goodluckmich]

In my Perl code I aim to compute the Gaussian integral, and the Gaussian function is expressed as

###code###
sub func
{
my $x = shift;
return (1/(sqrt($Vz*2*3.1416)+0.000001))*exp(-(($x-$Mz)**2)/((2*($Vz**2))+0.000001));
}
###code###

, where I integral from 0 to 1, and $Vz is the variance and $Mz is the mean. 0.000001 is used to avoid the illegal division by zero. However my script will just stop at some point during execution and not proceed anymore. I tried to debug, and figured out it "seemed" to be the problem of the part "exp(...)", because if I replaced the exp() with an arbitrary constant, say 1.5, the script would just work well. However I just didn't get what's wrong with the exp(...) code. It seemed pretty correct to me. Could anyone please help me on this? Thank you very much!!!

 

[goodluckmich]

Sorry I should've followed the "code" rules. Here is my code - thanks!!!

sub func
{
    my $x = shift;
    return (1/(sqrt($Vz*2*3.1416)+0.000001))*exp(-(($x-$Mz)**2)/((2*($Vz**2))+0.000001));
}

 

[rharsh]

What are some valid values for $x, $Vz and $Mz? Also, with your given values, what is the expected output of func()?

I plugged in some arbitrary values to the function you provided and it spit out an answer. I don't know if the output is right, but it's working.

 

[MillerH]

Your code appears to be fine. I cannot imagine what might be leading exp to cause any problems, so I think it's probably something else. The only thing that I would suggest that you do is to treat define by 0 a little more explicitly, instead of introducing deviation from your expected value.

sub func
{
    my $x = shift;
    return 0 if $Vz == 0; # Avoid divide by Zero. (could also just die)
    return (1/(sqrt($Vz*2*3.1416))) * exp( -(($x-$Mz)**2)/(2*($Vz**2)) );
}