1. Set default for N, seems to give more stable results. 2. add reference to Zaykin to docstring 3. split calculation, seems to make things a bit more stable.
1. Set default for N, seems to give more stable results.
2. add reference to Zaykin to docstring
3. split calculation, seems to make things a bit more stable.

brentp/combined-pvalues,brentp/combined-pvalues