Re: Table of tables
- To: mathgroup at smc.vnet.net
- Subject: [mg113275] Re: Table of tables
- From: Sebastian Schmitt <sschmitt at physi.uni-heidelberg.de>
- Date: Thu, 21 Oct 2010 07:04:07 -0400 (EDT)
Dear all! Luiz was looking for a general solution how to act only on the third component of his vectors. I came up with this: t = {{{-1, -1, -2}, {-1, -1, -3}}, {{-1, -1, -4}, {-1, -1, -5}}}; Map[Apply[Function[{x, y, z}, {x, y, z + a}], #] &, t, {2}] {{{-1, -1, -2 + a}, {-1, -1, -3 + a}}, {{-1, -1, -4 + a}, {-1, -1, -5 + a}}} Here you see that I work only on the third component adding "a". What do you think? Cheers, Sebastian Luiz Melo wrote: > Thanks Sebastian and Valeri for the help. > > I'm actually looking for a function that operates only on the third row of each > column-matrix terms(which happen to be complex in the example I gave), but > leaves the other terms intact. Consider a different example: > > Let > t = {{{-1, -1, -2}, {-1, -1, -3}}, {{-1, -1, -4}, {-1, -1, -5}}}; > > how can I get > > {{{-1, -1, 2}, {-1, -1, 3}}, {{-1, -1, 4}, {-1, -1, 5}}}; > > that is, in this case, I need a function that takes the Abs[] of the 3rd row of > each sub-matrix and leaves the other terms intact. > > Regards, > Luiz > > > >> Hi Luiz! >> >> Luiz Melo wrote: >> > Given >> > >> > t = {{{-1, -1, -2+2I}, {-1, -1, 3-I}}, {{-1, -1, 4+I}, {-1, -1, -5-5I}}}; >> > >> > how can I extract the imaginary part of the complex elements to obtain >> > >> > {{{-1, -1, 2}, {-1, -1, -1}}, {{-1, -1, 1}, {-1, -1, -5}}}; >> >> What about: >> >> Function[{e}, If[Im[e] == 0, e, Im[e]], Listable][t] >> >> There seems to be no ComplexQ therefore I test with "Im[e] == 0" if it >> is not a complex number. >> >> Cheers, >> >> Sebastian >> > > > --