I use gnuplot for plotting functions. This is my script at the moment:

```
set terminal png xffffff x222222
set output "Ausgleichszahlungen.png"
set title "Ausgleichszahlungen"
set xlabel 'F_MZ / A_MZ'
set ylabel 'Faktor F'
set xrange [0.5:1]
set yrange [0:1]
set key off
set xzeroaxis linetype -1 linewidth 0.5
set yzeroaxis linetype -1 linewidth 0.5
set xtics 0.1
set ytics 0.1
f(x) = 0.75 * (1-x) - 317.0 / 20000
g(x) = 5.0/26 * (1-x) ** 2 + 35.0/52 * (1-x) - 2121.0 / 260000.0
h(x) = 13.0/7 * (1-x) ** 2 + 11.0/25 * (1-x)
plot f(x), g(x), h(x)
```

f(x), g(x) and h(x) are one function:

-infinity < x < 0.8 : f(x)

0.8 <= x < 0.93 : g(x)

0.93 <= x < +infinity: h(x)

How can I do this?