Ensure all constants are double precision to prevent differences with  C examples due to casting.
Ensure all constants are double precision to prevent differences with 
C examples due to casting.


svn path=/trunk/; revision=8607

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