Hi Bartek,
On Mon, 14 Feb 2005, Bartosz Lew wrote:
eemmm, I'm about to finish my own versio of a program that calculates circles on the sky for dodecahedron. :) I was just wandering about the correlator you used. I have 2 remarks:
- circles of different sizes are represented by different number of
pixels. so naturally bigger circles will have bigger S value that the smaller because there is just simply more terms to sum over. like T_i*T_j from 'upper' and 'lower' circle. I'm trying to use the same correlator but normalized to one pixes - i.e. I divide each S value (for each individual circle) by the number of pixels that go into it. What do you think about that ?
See eq.(9) astro-ph/0402608. The only difference is the normalisation.
- I'm a bit worried about the fact that you don't use absolue values in
the \delta T_i and \delta T_j. Imagine a fluctuations aroud the circle in shape of just a linear function T(dist_along_circle=d) ~ d and indentical in the opposite circle. whaen you correlate this you get zero - that's not
You don't get zero. \int_0^L d*d dd = L^3/3 - 0 = (L^3)/3 which is bigger than zero.
much. I know it's not a prove but looks a bit worrying to me,since
It's wrong, so IMHO it's not a proof.
probably some , any random fluctuations can generate S > 0, while for the perfect match we get S=0. So I indent to use abs(T_i)*abs(T_j) (except from the normalization thing).
That will increase the false signal. ok, next two emails...
pozdr boud