f(x) = log(x)
xtendvers = 1 (slider from 1 to 50, step 2)
M: (xtendvers, f(xtendvers))
P: (xtendvers, 0)
N: (0, f(xtendvers))
mn = Segment(M, N)
mp = Segment(M, P)
A1: "x(" + (Name[M] + ")")
B1: "y(" + (Name[M] + ")")