f(x) = a+b*sin(omega*x+c)
 a=0.00001
 b=-1
 c=pi/2
 omega=2*pi/4.8
reset
set xrange [0:5]
set samples 10000
fit f(x) file u ($14*1.e6):13  via a,b,c, omega
set xrange [0:20]
fit f(x) file u ($14*1.e6):13  via a,b,c, omega
plot file u ($14*1.e6):13 w l, f(x)
set xrange [0:40]
fit f(x) file u ($14*1.e6):13  via a,b,c, omega
plot file u ($14*1.e6):13 w l, f(x)
set xrange [0:100]
fit f(x) file u ($14*1.e6):13  via a,b,c, omega
plot file u ($14*1.e6):13 w l, f(x)
set xrange [0:200]
fit f(x) file u ($14*1.e6):13  via a,b,c, omega
plot file u ($14*1.e6):13 w l, f(x)

set xrange [0:400]
fit f(x) file u ($14*1.e6):13  via a,b,c, omega
plot file u ($14*1.e6):13 w l, f(x)
if(omega0==0.)omega0 = omega



 g(x) = a1+b1*sin(omega1*x+c1)
 a1=0.00001
 b1=1.8
 c1=0.00001
 omega1 = 1.6163*(abs(v)/90.)**.5

if(v<0){
reset
set xrange [0:5]
set samples 10000
fit g(x) file u ($14*1.e6):6  via a1,b1,c1, omega1
set xrange [0:20]
fit g(x) file u ($14*1.e6):6  via a1,b1,c1, omega1
plot file u ($14*1.e6):6 w l, g(x)
set xrange [0:40]
fit g(x) file u ($14*1.e6):6  via a1,b1,c1, omega1
plot file u ($14*1.e6):6 w l, g(x)
set xrange [0:100]
fit g(x) file u ($14*1.e6):6  via a1,b1,c1, omega1
plot file u ($14*1.e6):6 w l, g(x)
set xrange [0:200]
fit g(x) file u ($14*1.e6):6  via a1,b1,c1, omega1
plot file u ($14*1.e6):6 w l, g(x)
set xrange [0:400]
fit g(x) file u ($14*1.e6):6  via a1,b1,c1, omega1
plot file u ($14*1.e6):6 w l, g(x)
}

print file,"   ", omega,"   ",v,"    ",omega-omega0,"   ",omega1