Synchronised example x21c with its C++ counterpart - isnan() issue
Synchronised example x21c with its C++ counterpart - isnan() issue

svn path=/trunk/; revision=7019

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot