f(x)=a*exp(-((x-b)/c+(exp(-(x-b)/c)))/2)
a=1400
b=170
c=90
fit[100:250] f(x) "sr-hideaki.hist" using 1:2 via a,b,c 
#fit[ 100:200] f(x) "sr-hideaki.hist" using 1:2 via a,b,c
plot f(x), "sr-hideaki.hist"