Re: apparently I don't know how to use Map (or Apply or MapThread)
- To: mathgroup at smc.vnet.net
- Subject: [mg77394] Re: apparently I don't know how to use Map (or Apply or MapThread)
- From: Valeri Astanoff <astanoff at gmail.com>
- Date: Thu, 7 Jun 2007 04:10:51 -0400 (EDT)
- References: <f4676i$1n3$1@smc.vnet.net>
On 6 juin, 13:52, dbsearc... at yahoo.com wrote: > I started with this: > > m = {{0.098, 0.951, 0.954}, {0.509, 0.914, 0.487}} > > I tried to do this > > Table[#[[i, i]], {i, Length[#]}] & /@ m > > It does not work, but this works > > Diag := Function[x, Table[x[[i, i]], {i, Length[x]}]]; Diag[m] > > !@#$%^&*( > > Can anyone tell me why? I also tried: Apply, MapThread, > DiagonalMatrix, TakeMatrix, adding () around the pure function... > > I know that this is a simple problem. Would Evaluate help? > > TIA. > > Regards.. In[1]:= m={{0.098,0.951,0.954},{0.509,0.914,0.487}}; In[2]:=Tr[m,List] Out[2]={0.098,0.914}