Re: Surviving 'Illegal division by zero'

[wufnik]

eval is fine for some things, but if i were dealing with a lot of data here, it might be of interest to me to consider 0 values as 'very very small' values, and transpose the problem to the numerical sphere.

the relevance of this approach depends on your data: but eval can be costly if i were dealing with mines of it. in addition, using a numerical approach allows you to 'take in' the points around 0 if you are creating a distribution, for instance - which stripping them out with an eval does not.

so, simply: transform the data by a adding a wee wee float, apply your calculation, then strip out aberrant $growths - if you are not fond of them. ie:

my $fig_1 = get_numeric_value_from_xml(...);
my $fig_2 = get_numeric_value_from_xml(...);
my $growth;
my $ff = 1.175E-38;

$growth = ( $fig_2 / ($fig_1 + $ff) * 100 ) - 100;

don't hold me responsible for this choice of $ff. you may have to adjust this to another (bigger) small figure depending on your data. cya just treat 0 as