search for: xprod

A common point made in discussion of contrasts, type I, II, III SS etc is that for sensible comparisons one should use contrasts that are 'orthogonal in the row-basis of the model matrix' (to quote from http://finzi.psych.upenn.edu/R/Rhelp02/archive/111550.html) Question: How would one check, in R, that this is so for a particular fitted linear model object? Steve Ellison

Hi all, How can I tell RGL to set the center for the rotation to the origin of the coordinate system (0,0,0). It seems that the default is to use the center of the display not the origin of the coordinate system. open3d() lines3d(c(0, 1), c(0,0), c(0,0)) lines3d(c(0,0), c(0, 1), c(0,0)) lines3d(c(0,0), c(0,0), c(0, 1)) TIA Mark ??????????????????????????????????????? Mark Heckmann Blog:

Hi all, I have been searching all sorts of documentation, reference cards, cheat sheets but can't find why R's crossprod(A, B) which is identical to A%*%B does not produce the same as Matlabs cross(A, B) Supposedly both calculate the cross product, and say so, or where do I go wrong? R is only doing sums in the crossprod however, as indicated by (z <- crossprod(1:4)) # = sum(1 +

Can anybody point me at any resources that would explain how to optimize mdct_backward for a cpu with a fused multiply-accumute unit? >From what I understand from responses to my older postings, Tremor's mdct_backward could be rewritten to take advantage of a muladd. My target machine can do either two-wide 32x32 + Accum(64) -> Accum(64) integer muladd or eight-wide 16x16 + Accum(32)