splot-data-linear.dat

-3 1 9
-3 2 9
-3 3 9

-2 1 4
-2 2 4
-2 3 4

-1 1 1
-1 2 1
-1 3 1

0 1 0
0 2 0
0 3 0

1 1 1
1 2 1
1 3 1

2 1 4
2 2 4
2 3 4

3 1 9
3 2 9
3 3 9