Re: copying values of entries between matrices

*To*: mathgroup at smc.vnet.net*Subject*: [mg78014] Re: [mg77952] copying values of entries between matrices*From*: Curtis Osterhoudt <cfo at lanl.gov>*Date*: Thu, 21 Jun 2007 05:48:04 -0400 (EDT)*Organization*: LANL*References*: <200706200937.FAA10111@smc.vnet.net> <200706201240.58706.cfo@lanl.gov>*Reply-to*: cfo at lanl.gov

I screwed up on what I was calling matrices in my reply. In my reply, please replace "s" and/or "dOneCol" with your "entMat", and set "dOneCol" equal to the result! Sorry for the mix-up on my part. C.O. On Wednesday 20 June 2007 12:40:58 Curtis Osterhoudt wrote: > If you have v. 6 of Mathematica, the function "diagonal" should help you > out; to get a list of the elements you want, try > > Diagonal[s, #]&/@Range[-(Length@s) + 1, 0] > > Of course, if you want these elements on the same level in your dOneCol, > > Flatten@Diagonal[s, #]&/@Range[-(Length@s) + 1, 0] > > > > If you have an earlier version, you could try something like the following > (which I haven't optimized for different types of lists or anything, but > should work for matrix arguments): > > takeLowerLeft[mat_]:=Take[mat, {2, Length@mat}, {1, Length@mat - 1}] > > snagDiags[mat_] := mat[[#, #]] & /@ Range[Length[mat]] > > snagDiags /@ NestList[ takeLowerLeft, dOneCol, Length[dOneCol] -1 ] > > Flatten@% > > > > Hope that helps! > > C.O. > > On Wednesday 20 June 2007 03:37:37 text.tex wrote: > > Hi, > > here is my problem: > > I have a 18x18 matrix called entMatr. > > I want to copy the values of the elements of the lower left half of > > entMatr into a 171x1 matrix called dOneCol. > > I had tried a 3-nested loop for copying the values from entMatr to > > dOneCol; the current version where I tried to replace the loop over > > the rows of dOneCol with a counter q produces a result, however the > > result is not what I want... > > > > I'd greatly appreciate any pointers how to get this working! > > Thanks, > > Claus > > > > This is what I tried: > > > > <pre> > > (* initialize entMatr *) > > entMatr = Table[Subscript[m, i, j], {i, 18}, {j, 18}]; > > > > (* fill the lower left half of entMatr with some values *) > > For[i = 1, i < 18 + 1, i++, > > For[j = i, j < 18 + 1, j++, > > entMatr[[j, i]] = i > > ] > > ] > > > > (* initialize dOneCol *) > > dOneCol = Table[Subscript[n, x], {x, 171}]; > > > > (* attempt to copy the values from entMatr to dOneCol *) > > q = 0; > > For[k = 1, k < 18 + 1, k++, > > For[p = k, p < 18 + 1, p++, > > dOneCol[[q]] = entMatr[[p,k]] > > q++ > > ] > > ] > > dOneCol > > </pre> -- ========================================================== Curtis Osterhoudt cfo at remove_this.lanl.and_this.gov PGP Key ID: 0x4DCA2A10 Please avoid sending me Word or PowerPoint attachments See http://www.gnu.org/philosophy/no-word-attachments.html ==========================================================

**References**:**copying values of entries between matrices***From:*"text.tex" <Clausenator@gmail.com>