Path: csiph.com!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail From: jimp@specsol.spam.sux.com Newsgroups: sci.physics Subject: Re: Where did the 3 geometric dimensions come from? Date: Sun, 26 Jun 2016 02:04:15 -0000 Organization: A noiseless patient Spider Lines: 55 Sender: Jim Pennino Message-ID: References: <83e34d-dng.ln1@mail.specsol.com> <1f413ekmspyea.vlgpozkrz02f$.dlg@40tude.net> Injection-Info: mx02.eternal-september.org; posting-host="db4120ef82bbc153014637d4cd15a795"; logging-data="32462"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+6MilOKRSXiWfk+OTkq85c" User-Agent: tin/2.2.1-20140504 ("Tober an Righ") (UNIX) (SunOS/5.10 (i86pc)) Cancel-Lock: sha1:BtcYKARoDTodsNogAKjb28tAyP8= Xref: csiph.com sci.physics:586729 ClutterFreak wrote: > On Sat, 25 Jun 2016 22:44:24 -0000, > jimp@specsol.spam.sux.com wrote: > >> ClutterFreak wrote: >>> On Fri, 24 Jun 2016 10:38:52 -0400, Michael J. >>> Strickland wrote: >>> >>>> We could easily number all locations in a cubical area with one >>>> coordinate starting at top left, near and progressing to bottom, right >>>> , far >>> >>> I'm not sure but I think computers store 3-D >>> information in that manner, using only one number to >>> find various parts of it. >> >> Ummm, no, computers store 3D information in whatever manner the programmer >> used, which could be anything. Generally it is in whatever is the easiest >> convention for the task at hand. >> >> The only computers I have ever heard of that knew anything about coordinates >> were purpose built analog computers that used spherical coordinates. >> >> The task of locating a freeway off ramp is very different than the task >> of defining an object for a 3D printer. >> >> > > Again I'm not sure (this is very old stuff I'm trying > to remember) but when you have, say, an array variable > like A(i,j,k) with i going from 1 to 10, j from 1 to > 100, and k from 1 to 5 computer allocates memory > locations for it that form a continuous chain of 5000 > location (each for a different value of that > variable). And when you want to retrieve what's stored > at A(3,70,4) computer does 3 + 70*10 + 4*100 = 1103 > and goes to 1103rd position along that chain to get > the value. It is similar to how Strickland wants to > access a cubic volume using only one number. > > But I'm not sure :) > > Of course you could force the computer store your data > in any strange way you want, but if you leave it to > computer to do it that's I believe it does it. How an array is stored is up to the compiler. http://stackoverflow.com/questions/2565039/how-are-multi-dimensional-arrays-formatted-in-memory https://en.wikipedia.org/wiki/Row-major_order -- Jim Pennino