Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!jarthur!nntp-server.caltech.edu!juliet.caltech.edu!gceych
From: gceych@juliet.caltech.edu (Eychaner, Glenn C.)
Newsgroups: comp.lang.c
Subject: ATAN2 and HYPOT functions for ints...
Message-ID: <1990Dec18.015344.19706@nntp-server.caltech.edu>
Date: 18 Dec 90 01:46:44 GMT
Sender: news@nntp-server.caltech.edu
Reply-To: gceych@juliet.caltech.edu
Organization: California Institute of Technology
Lines: 16
News-Software: VAX/VMS VNEWS 1.3-4x
Nntp-Posting-Host: juliet.caltech.edu

Ok, so here's my problem.
I am dividing two 512x512 arrays of unsigned char into 8x8 boxes, summing over
the boxes, and then shoving the results from the two arrays through atan2() 
and hypot().  The problem is: these function are awfully slow, as I have to
convert int (the result of the summing) to float, and then convert the result
back to int (unsigned char, actually).  Anyone got a faster way to do this?
No, LUTs, BTW, the "summing" has some added complications I won't mention which
increases the range of the numbers involved...
In other words, anyone got a hypot() or atan2() function which take and return
int?  (Note: atan2 should return a number in degrees if it returns int...)
                                                      Just wondering...
                                                      Glenn
Glenn Eychaner   |Eychaner@SunCub.Caltech.edu |Remember: It is easier to ride a
40386 N Shore Ln |gceych@iago.caltech.edu     |camel through the eye of a needle
Big Bear City, CA| Big Bear Solar Observatory |than to drive a Buick through the
            92314| !*** G O  N I N E R S ***! |hole in a doughnut.