I have data that looks like this:
1000 13 75.2
1000 21 79.21
1000 29 80.02
5000 29 87.9
5000 37 88.54
5000 45 88.56
10000 29 90.11
100
You also can use Gnuplot
which is also available from gretl
. Put your x y z data on a text file an insert the following
splot 'test.txt' using 1:2:3 with points palette pointsize 3 pointtype 7
Then you can set labels, etc. using
set xlabel "xxx" rotate parallel
set ylabel "yyy" rotate parallel
set zlabel "zzz" rotate parallel
set grid
show grid
unset key