A = 2.5 (slider from 0 to 5, step 0.1)
w = 8 (slider from 1 to 10, step 0.1)
dw = 1 (slider from 0 to 1, step 0.01)
phase = 0 (slider from 0 to 6.283185307179586, step 0.1)
S1(x) = A * sin(w * x)
S2(x) = A * sin((w + dw) * x + phase)
S(x) = S1(x) + S2(x)