Re: Could this be improved?

*To*: mathgroup at smc.vnet.net*Subject*: [mg21750] Re: [mg21741] Could this be improved?*From*: Hartmut Wolf <hwolf at debis.com>*Date*: Thu, 27 Jan 2000 22:56:32 -0500 (EST)*Organization*: debis Systemhaus*References*: <200001260845.DAA02354@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Jordan Rosenthal schrieb: > > 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 Hi Jordan, I suggest In[1]:= v = {1, 2, 3}; In[2]:= With[{r = Length[v] - 1}, Transpose[NestList[RotateRight, Join[v, Table[0, {r}]], r]]] // TableForm -- Hartmut

**References**:**Could this be improved?***From:*"Jordan Rosenthal" <jr@ece.gatech.edu>