You could also try looking at the implementation of the system expressions in System.cpp:

http://construct.svn.sourceforge.net/vi ... iew=markupThe

*ExpRoutineTable* array at line 436 maps the expression string (eg. "lerp") to the routine (&SystemObject::eLerp) - if you then search for SystemObject::eLerp (without ampersand) you'll find the implementation:

[code:1y4dyv82] 3887 long SystemObject::eLerp(LPVAL theParams, ExpReturn& ret)

3888 {

3889 // Calculate linear interpolation:

3890 // lerp(a, b, x) = a + x(b - a)

3891 double a = theParams[0].GetDouble();

3892 double b = theParams[1].GetDouble();

3893 double x = theParams[2].GetDouble();

3894

3895 return ret = Lerp(a, b, x);

3896 }

[/code:1y4dyv82]

You can use that to find the implementation of any system expression. Does that help?