When generating a sequence of random numbers you will notice that it tends to clump. Sometimes you want a bunch of samples that are better distributed, however. A sobol sequence is a series of random numbers which are relatively evenly distributed.
The seed allows you to select different sobol sequences. If it is a floating point seed, note very small differences will select very different sequences.
The offset is which entry in the sequence to extract. This should be an
integer sequence, like
ptnum, in order for the distribution property to work.
Each number is in the