f(x)\;=\;a\;log_b(x)

a = 1 (slider from -5 to 5, step 0.1)
b = 2 (slider from 0.1 to 10, step 0.1)
f(x) = a * log(x) / log(b)
texto1: "f(x) = " + a + " log_{" + b + "}(x)"
A: (1.0, f(1.0))
B: (b, f(b))