I'm a bit confused by the maxima solution. For example, A is both a specific node and it's also a 10 by 10 matrix. Similar for B. I can assume that the matrix values are something like potential contribution from the named node. But... k looks like the 10 10 #. of an index pair (with a bit of off-by-one since the maxima solution is using 1 based indices) except it's used as an index into A and B. And... so maybe A and B are really representing logically different kinds of data in different parts of their structure? But what is the logical structure then.
... anyways, the purpose of some of this code is not clear to me. -- Raul On Tue, Jan 8, 2013 at 9:16 AM, Aai <[email protected]> wrote: > You might check out the Rosetta code task > http://rosettacode.org/wiki/Resistor_mesh > > that has a link to this problem. The Maxima solution has an explanation > included. > > > > On 07-01-13 23:36, Raul Miller wrote: >> >> http://xkcd.com/356/ proposes a problem involving finding the >> resistance in a case involving an infinite number of resistors. >> >> Before I can reason about that graph, I'd want a systematic way of >> reasoning about much more trivial cases. >> >> So... here's a representation of a square with four corners: >> Resistors connect corner 0 with corner 1, corner 1 with corner 2, and >> both corners 1 and 2 with corner 3. Unnamed corner pairs are not >> connected. All resistors are 1 ohm. The expected net resistance >> between corner 0 and corner 3 should be 1 ohm. >> >> 1 ((, |.&.>)0 1;0 2;1 3;2 3)} <:%=i. 4 >> 0 1 1 _ >> 1 0 _ 1 >> 1 _ 0 1 >> _ 1 1 0 >> >> The values in this table represent the resistor connecting the two >> corners whose row/column indices represent the locations in the >> network. >> >> But.. how would I express this calculation without encoding the grid >> into the calculation itself? (In other words, so that any such >> resistance graph is allowed -- though it is ok to assume that the >> matrix describing the connections is symmetric.) >> >> This is probably fairly trivial for anyone with an EE background, but >> I'm not quite seeing how to approach this. >> >> Thanks, >> > > -- > Met vriendelijke groet, > @@i = Arie Groeneveld > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
