Fix in dipyramid initialization, where we had 0.25*25 as xk

Samo Penic

2012-07-09 443ba1603235e6cf668d0e24aa794c95941bc597

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Original written by Dan Kroll in FORTRAN. Code was then largely adapted and commented by Miha Fosnaric-Fosni. Rewritten into C by Samo Penic-Peni, with help of Miha's extensive explanations.