ncrat.lib
LIB "ncrat.lib"; ncInit(list("x", "y", "z")); ncrat f = ncratFromString("2*x*y"); print(f); ==> 2*x*y ncrat h1, h2; h1 = ncratInvert(f); print(h1); ==> inv(2*x*y) h2 = f ^ -1; print(h2); ==> inv(2*x*y)