Interesting. That "abs" is a typo for "fabs", but the two compilers I tested happened to have "double abs(double)", so I missed it. Thanks much for catching this.
Could you please change "abs(w)" in Line 232 of rgf1.2/src/tet/AzTree.cpp to "fabs(w)"?
If you run into further problems, please email to "Contact" in the readme.