Re: Getting coordinates of array member

*To*: mathgroup at smc.vnet.net*Subject*: [mg26263] Re: Getting coordinates of array member*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Sun, 10 Dec 2000 00:19:37 -0500 (EST)*Organization*: Universitaet Leipzig*References*: <90krir$r50@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, that looks not mich like a Mathematica question ? You may look at "The Art of Computer Programming" Volume I that contains an extensive chapter on linear addressing. You have a (n,m) array and (i,j)=(1,3) the linear index is k=j*n+i The reversion is done by j=Mod[k,n] i= k-j*n Regards Jens PS: Is it right that you transpose the index because 7 is on position (3,1) in your matrix? Stephane Hebert wrote: > > Hi folks, > > Ok, let's say I have this > > 1 2 3 > ----------- > 1| 1 2 3 > 2| 4 5 6 > 3| 7 8 9 > > A 3x3 matrice or array. Each number in the array represents its' position > from top left to bottom right. > > What I need to do is: > > Find what position 1,3 is. Just by looking at the array, we find that 7 is > the answer. > > Find what are the coordinates of 7. Again just by looking at the array we > see that the answer is 1,3 > > I need to come up with a simplu function that will return these. > > pos = GetPos(x,y) > > coord = GetCoord(pos) > > I've done this before, way long ago and can't find it. > > Thanks. > > -- > Stephane Hebert > ========================= > stephhebert at yourpants~videotron.ca > Remove yourpants~ to reply > =========================