f_1(x) = (x + 1.0) * (x - 1.0) * (x - 3.0) + 0.040000000000000036
f_2(x) = -f_1(x)
f_3(x) = (x + 2.0)^(2.0) * (x - 1.0)
f_4(x) = (x + 1.98) * (x - 1.02)^(3.0)
Funktionsnummer = 1 (slider from 1 to 4, step 1)