comp.lang.idl-pvwave archive: archive » Re: Finding all angles within a range of directions; an algorithm question

Home » Public Forums » archive » Re: Finding all angles within a range of directions; an algorithm question

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Finding all angles within a range of directions; an algorithm question [message #30315 is a reply to message #30265]

Tue, 16 April 2002 09:08

tbowers0
Messages: 11
Registered: August 2001

Junior Member

> One simplification: in (4), skip taking the acos of the dot products.
> All of the angles you want will have positive dot products; just throw
> out the negative ones.
>
> -- Mark

Oh! Good point. I still would like to keep it general though because I
may sometimes use a smaller 'acceptance angle'. Eg, get all values
with 45 degree half angel rather than the plate's 90 degrees.
But, it definately seems appropriate to put a check on the front to
see and save from unnecessary function calls, like

if (sensorHalfAngle eq 90) then begin
;just dot product and where(dotProduct ge 0.0),
;no need to acos()
...
endif else begin
;angle not over a flat plat, so dot product
;then calc. psi=acos(dotProduct), then where(psi le 90.0)
...
endelse

Thanks Mark

Report message to a moderator

[Message index]

		Re: Finding all angles within a range of directions; an algorithm question By: Struan Gray on Mon, 15 April 2002 06:18
		Re: Finding all angles within a range of directions; an algorithm question By: Mark Zimmerman on Thu, 11 April 2002 14:29
		Re: Finding all angles within a range of directions; an algorithm question By: tbowers0 on Tue, 16 April 2002 09:08
		Re: Finding all angles within a range of directions; an algorithm question By: tbowers0 on Tue, 16 April 2002 08:56

Previous Topic:	generalized eigenvectors
Next Topic:	memory problems on Win2000 or how to delete a variable

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sun Oct 12 16:51:51 PDT 2025

Total time taken to generate the page: 0.87913 seconds