Talk:Resistor mesh: Difference between revisions

non, wrong, these are equations between voltages, and V(A)=0, the current in B comes from V(B)=RI+V(A)=RI
(non, wrong, these are equations between voltages, and V(A)=0, the current in B comes from V(B)=RI+V(A)=RI)
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:: Of course the interesting part is how to get the voltage values, and there are multiple ways to do it. The C code just give the circuit some arbitrary values initially, then at each iteration calculates how much voltage difference is needed on each node to locally sastisfy the current flow constraint on that node, and adds it onto the voltage. For this task it converges and pretty quickly at that. --[[User:Ledrug|Ledrug]] 15:45, 29 August 2011 (UTC)
:::Given the problem size, even Gauss pivoting will do. Now, for a larger circuit, you would simply use a sparse symmetric solver, and there are many good ones already written. Maybe conjugate gradient would be a nice starting point. See also Maxima solution for an exact value. At least it will help checking other methods ;-) [[User:Capra Hircus|Capra Hircus]] 11:11, 28 August 2012 (UTC)
 
== A doubt about the equations... ==
 
When I wrote the Maxima solution along with a long comment in 2012, I may have missed something. I got the same answer as everybody, so it looked fine, but now I have a doubt. When using Kirchhoff's current law, there is a constant current 1A appearing at node B. Why is there no constant current -1A at node A ? The problem is solved by putting a constant current source between A and B and 'measuring' voltage, thus there is a current that 'arrives' at B, and the same that 'leaves' from A. Of course the solution would be completely different. Any idea about this issue? I have added a Python solution using Gauss pivoting, and with this -1, to show the different value, in case someone wants to check.
 
Tihs is just an idea, I got my last EE courses long ago, and this may be a bit crazy, but I thought I would share this doubt with you, just in case...
 
[[User:Arbautjc|Arbautjc]] ([[User talk:Arbautjc|talk]]) 12:49, 30 January 2015 (UTC)
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