a1 = -1 (slider from -5 to 5, step 0.1)
a2 = 1 (slider from -5 to 5, step 0.1)
u1 = 1 (slider from -5 to 5, step 0.1)
u2 = 2 (slider from -5 to 5, step 0.1)
a3 = 1 (slider from -5 to 5, step 0.1)
u3 = -1 (slider from -5 to 5, step 0.1)
f(x) = a1 * abs(x - u1) + a2 * abs(x - u2) + a3 * abs(x - u3)