am I missing something? Why not just use Statistics to do this directly on the vectors? I don't recall if it operates on vectors as 3 components or by computing the mean first; but if it does operate on the 3 components (not what you want) then do the mag first using compute then pass to Statistics to get the sd of the magnitude. Donna
_________________________________ Donna L. Gresh, Ph.D. Visual Analysis Group IBM T.J. Watson Research Center (914) 784-5049 [EMAIL PROTECTED] Chris Pelkie <[EMAIL PROTECTED]>@opendx.watson.ibm.com on 11/22/2000 10:41:10 AM Please respond to opendx2-users@lists.berlios.de Sent by: [EMAIL PROTECTED] To: opendx2-users@lists.berlios.de cc: Subject: Re: [opendx-users] standard deviation >Hello, > >I¥m trying to figure out how it is possible to calculate the standard >deviation >of the values of a vector and display it. It does not seem that the compute >module supports this. >For example: i have a vector called b with three elements. first, i calculate >the magnitude of the vector using mag(b). then, i need to calculate the mean >value of mag(b). After that, the standard deviation operator has to be applied >to mag(b) and mean(mag(b)). >Is there any possibility to accomplish this in opendx? > > As you know, s.d. requires a global value (mean). It is possible to iterate in DX over a set of values using Get/Set pairs (best done in a macro using GetLocal/SetLocal). But, this is very inefficient and painfully slow if you need to do more than a few iterations, or if you expect real-time sorts of responses. Better to precalculate this info and import s.d. as a separate component mapped to the same positions as the vectors are. Chris Pelkie Practical Video, LLC 30 West Meadow Drive Ithaca, NY 14850 (607) 257-8335 [EMAIL PROTECTED]
