Re: Could this be improved?---Continued

*To*: mathgroup at smc.vnet.net*Subject*: [mg21805] Re: Could this be improved?---Continued*From*: "Jordan Rosenthal" <jr at ece.gatech.edu>*Date*: Fri, 28 Jan 2000 01:45:55 -0500 (EST)*Organization*: Georgia Institute of Technology, Atlanta GA, USA*References*: <86mdpv$2f3@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi all, First of all I wanted to say thanks. I got more than ten replies (not all were posted to the newsgroup) to my message and all replies were informative. To continue my learning experience, I wanted to take all the different methods and compare the timings to see which runs fastest. I tried the following: Timing /@ {f1[vSmall];, f2[vSmall];, f3[vSmall];, f4[vSmall];, f5[vSmall];, f6[vSmall];, f7[vSmall];, f8[vSmall];, f9[vSmall];, f10[vSmall];, f11[vSmall];, f12[vSmall];, f13[vSmall];, f14[vSmall];, f15[vSmall];} where f1,f2,...,f15 are the different function implementations I received (can you believe there were that many!). This does not work. I get 0 seconds for each. I imagine this is because each f[vSmall] term in the list is being evaluated before Timing is applied. Is that correct? So I have two more questions: 1) Is there any way to stop the function evaluation from happening until Timing gets applied to it? I looked at the Hold command and its variants, but I could not figure out how best to apply it. Am I on the wrong track? 2) I know you can use the Map function (or the /@ form) to apply a function to a list of elements. Is there a way to apply a list of functions to a single element? For example, it would be nice if I could apply each function in the list{f1,f2,f3,f4,f5,f6,f7,f8,f9,f10,f11,f12,f13,f14,f15} to the vector vSmall. Thanks ahead of time, Jordan "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 > > > > >