f(x)=a*exp((-(x-b)/c-exp(-(x-b)/c))/2)
a=400
b=4
c=0.1
fit [0:20] f(x) "copy\ Sr\ 1.48kV\ hikaru_s.txt" using 2:3 via a,b,c
set grid
set xlabel "Channel"
set ylabel "Count"
set xrange[0:20]

plot "copy\ Sr\ 1.48kV\ hikaru_s.txt" using 2:3,f(x)

set terminal postscript enhanced color
set output "test3.ps"
replot
set output
set terminal windows