question: public static double log10 ( double val ) { if ( val > 0.0 ) return Math . log10 ( val ) ; return HUGE_NEGATIVE ; }
target:  Adjusted log10 to handle values less or equal to zero. <p> The logarithm does not result in real numbers for arguments less or equal to zero, but the plot should still somehow handle such values without crashing. So anything &le; 0 is mapped to a 'really big negative' number just for the sake of plotting. <p> Note that LogarithmicAxis.java in the JFreeChart has another interesting idea for modifying the log10 of values &le; 10, resulting in a smooth plot for the full real argument range. Unfortunately that clobbers values like 1e-7, which might be a very real vacuum reading.