gnuplot
gnuplot is another option for building diagrams within org-mode.
reset
set title "GNUPlot example"
set xlabel "X"
set xrange [-8:8]
set xtics -8,2,8
set ylabel "Y"
set yrange [-20:70]
set ytics -20,10,70
f(x) = x**2
g(x) = x**3
h(x) = 10*sqrt(abs(x))
plot f(x) w lp lw 1, g(x) w p lw 2, h(x) w l lw 3