> > And why is P(t) from t=0 to 1 when surely it's from > > t[min] = t[k] = 0, to t[max] = t[n+2] = 4 ?? > > Still don't know the answer to that though OK I think that follows from Vincent's answer - if we were taking the whole circle, P(t) would be for 0<=t<4, but since we're only doing a quarter circle, equivalent to just using [0 0 0 1 1 1], then t[max] = 1. Raymond