set parametric
gauss(x,c)=exp(-(x-c)**2/10000)
geel(x)=gauss(x,600)
groen(x)=gauss(x,500)
blauw(x)=gauss(x,400)
set trange [100:900]
set logscale
plot geel(t) + groen(t),geel(t) + blauw(t)