set term pdf fontscale 0.75 size 6in,4in font "Times-New-Roman,12"
outfile = 'quad_field.pdf'
set output outfile
f(x) = a+b*x + c*x*x +d*x*x*x +e*x**4+f*x**5
fit f(x) 'quad_field.dat' u ($1*1000):($2/1000/100) via a,b,c,d,e,f
set xlabel 'Displacement [mm]' offset 20,0
set xrange [-45:45]
set ylabel 'Efield [kV/cm]' offset 0,5
set key left Left reverse
plot 'quad_field.dat' u ($1*1000):($2/1000/100) w p ps .7 pt 6 t 'Field map', f(x) lt -1 t 'Multipole Expansion'
g(x) = a + b*x
set ylabel '(E - E_0)/E_0 [%]'
#plot (f(x)-g(x))/g(x) *100 not
print outfile