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["张林" <xtss_0002@xxxxxxxxxxxx>]

Hi everyone
These days I'm a little puzzled with the strain compution in TriaxialstressController.cpp ,just as follows:

strain[0] = Mathr::Log(width0/width);//Eq(1)
strain[1] = Mathr::Log(height0/height);//Eq(2)
strain[2] = Mathr::Log(depth0/depth);//Eq(3)
volumetricStrain=strain[0]+strain[1]+strain[2];//Eq(4)

IIRC,Log means not log10 but ln as usual .Is it right? 
Eq(1 to 3) is different from the common compution of strain like:
epsilon=(length-length0)/length0 
and, in PFC3D manuals(V3.0)->users' guide->problem solving with pfc3d Page 47, I found another Eq for strain compution:
epsilon=(L-L0)/((L0+L)/2)
Are the 3 methods all right? They're designed for different fields? 

Thanks for any suggestion.
Regards.
Zhang Lin
　　　　　　　　xtss_0002@xxxxxxxxxxxx
　　　　　　　　　　2008-11-25