reset

set title "Linsenabstand 9,35 cm"
set xlabel "[1 + 1/\gamma]"
set ylabel "[x in cm]"
set grid xtics ytics
set key top left

f(x) = m * x + a
g(x) = c * x + d

fit f(x) 'DatenAbbe2.txt' us ($2):($1) via m,a
fit g(x) 'DatenAbbe2.txt' us ($3):($1) via c,d

plot \
'DatenAbbe2.txt' us 2:1 title "normales System" lt 1, \
f(x) title "Ausgleichsgerade g1 (normal)" lt 1, \
'DatenAbbe2.txt' us ($3):($1) title "gedrehtes Sytem" lt 3, \
g(x) title "Ausgleichsgerade g2 (gedreht)" lt 3

set output "abbe2.eps"
set term postscript enhanced eps color; replot