coef(cos3phi, coef0, a, b) = coef0*(a*cos3phi + b)

Qs_m1 = 3.
Qs_p1 = 4.
a_Qs = (Qs_p1/Qs_p1 - Qs_m1/Qs_p1)/2.
b_Qs = Qs_p1/Qs_p1 - a_Qs

mu1_m1 = 60.
mu1_p1 = 50.
a_mu1 = (mu1_p1/mu1_p1 - mu1_m1/mu1_p1)/2.
b_mu1 = mu1_p1/mu1_p1 - a_mu1

mu2_m1 = 1.
mu2_p1 = 2.
a_mu2 = (mu2_p1/mu2_p1 - mu2_m1/mu2_p1)/2.
b_mu2 = mu2_p1/mu2_p1 - a_mu2



set xrange[-1:1]
p   coef(x,  4.,  1.1,  2.) t 'Qs' w lp
p   coef(x,  Qs_p1,  a_Qs,  b_Qs) t 'Qs' w lp
rep coef(x, mu1_p1, a_mu1, b_mu1) t 'mu1' w lp
rep coef(x, mu2_p1, a_mu2, b_mu2) t 'mu2' w lp
pause -1

show var
