Re: Could this be improved?
- To: mathgroup at smc.vnet.net
- Subject: [mg21757] Re: Could this be improved?
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Thu, 27 Jan 2000 22:56:38 -0500 (EST)
- References: <86mdpv$2f3@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Jordan: myMtx[v_] := Reverse[Partition[PadLeft[Reverse[#], 3#2 - 2, {0}, #2 - 1], #2, 1]] &[v, Length[v]] myMtx[{1, 2, 3}] {{1, 0, 0}, {2, 1, 0}, {3, 2, 1}, {0, 3, 2}, {0, 0, 3}} -- Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 "Jordan Rosenthal" <jr at ece.gatech.edu> wrote in message news:86mdpv$2f3 at smc.vnet.net... > Hi all, > > I wrote the following code which works correctly. I was wondering, however, > if there was a way of doing the same thing that had more of a Mathematica > approach. I am new to Mathematica and am still trying to get a grasp on how > to program effectively within the environment. > > myMtx[v_] := Module[ > {nCols, nRows, vPadded, c}, > nCols = Length[v]; > nRows = 2nCols - 1; > c = ZeroMatrix[nRows, nCols]; > vPadded = PadRight[v, nRows, 0]; > For[i = 1, i <= nCols, i++, > c[[All, i]] = vPadded; > vPadded = RotateRight[vPadded] > ]; > c > ] > > For example, myMtx[{1,2,3}] takes the vector {1,2,3} and turns it into the > matrix {{1, 0, 0}, {2, 1, 0}, {3, 2, 1}, {0, 3, 2}, {0, 0, 3}} which looks > like > > [ 1 0 0 ] > [ 2 1 0 ] > [ 3 2 1 ] > [ 0 3 2 ] > [ 0 0 3 ] > > > Thanks, > > Jordan > > > > >