matthew-brett/nipy — comment on commit 6151067629171674174003edaa940ad528ce2a1d
File: nipy/algorithms/statistics/intvol.pyx line 46
By matthew-brett:

Ah yes - I saw that - but that page refers (I think) to the dot product of the subtraction of the points, but here we have the dot product of the points coordinates, including the dot products of the points with themselves. I tried reducing the resulting formula from this code, with sympy, but it doesn't reduce immediately to the formula on the page, at least, not when I tried it at a first pass. I'll have a look at the stuff that Jonathan posted and see if I can get further in understanding, but any pointers would be very useful.