This keyword sets the number of (integer) divisions along the whole unit cell edges for the fast, medium and slow axes. Which axis is fast, medium and slow is determined by the PERMutation keyword. To keep the FFT as fast as possible, GraphEnt will only cooperate if the grid sizes are any of the following :
1, 2, 4, 6, 8, 10,
12, 14, 16, 20, 24, 28,
30, 32, 40, 42, 48, 56,
60, 64, 70, 80, 84, 96,
112, 120, 128, 140, 160, 168,
192, 210, 224, 240, 256, 280,
320, 336, 384, 420, 448, 480,
512, 560, 640, 672, 768, 840,
896, 960, 1024
If you need more than 1024 grid points on any axis, then you are better off finding a
program encoding for a more efficient maximum entropy
algorithm (because with GraphEnt you will probably never finish the calculation).