Re: converting table output and plotting

*To*: mathgroup at smc.vnet.net*Subject*: [mg49115] Re: converting table output and plotting*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Thu, 1 Jul 2004 05:26:38 -0400 (EDT)*Organization*: The University of Western Australia*References*: <cbu2kr$5i6$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

In article <cbu2kr$5i6$1 at smc.vnet.net>, "seferiad" <seferiad at pacbell.net> wrote: > Hello, > I have the following equation: > > Table[{v, NSolve[{i == v/r2 + i1, i1==i1(r1+r2)/r2 + a/r2*Log[i1/io + > 1] - v/r2} /. {r2 -> 200, r1 -> .025, io -> 10^-9, a -> .05}, {i, > i1}]},{v, 1, 1.2, .1}]//ColumnForm > > > OUTPUT IS: > > {1, {{i->.402, i1->.397}}} > {1.1{{i->1.611,i1->1.60}}} > {1.2,{{i->3.86, i1->3.85}}} > > > The first terms 1, 1.1,1.2 are Voltage (v) and the second term is > Current (i), the third term is Current1 (i1). > > My objective is to vary my equation above and then create the output > in such a form that I can directly plot v vs. i, that is "1st term" > vs. "2nd term". Unfortunately, I don't know how to do this since the > outputs in the table aren't as I like. > > Note: My original approach was to write the transcendental equation in > a single form whereby, NSolve[ i == function (v, i) ] Unfortunately, > Mathematica seems to choke on this one. By calculating an additional > (uninteresting) value (namely, v1), it gives me the output I'm looking > for. Again, except that I don't know how to convert this into a set of > numbers that I can plot. Your set of equations can be solved exactly for i and i1: solution = Solve[{i == v/r2+i1, i1==i1(r1+r2)/r2+a/r2 Log[i1/io+1]-v/r2},{i, i1}] A table of numerical values agrees with those obtained using NSolve: parameters = {r2 -> 200, r1 -> 0.025, io -> 10^(-9), a -> 0.05}; Table[{v, solution /. parameters}, {v, 1, 1.2, 0.1}] You can plot the solution v versus i as follows: ParametricPlot[Evaluate[{i, v} /. solution /. parameters], {v, 1, 2}, AxesLabel -> {i, v}] (You could just use Plot to visualize i versus v). Cheers, Paul -- Paul Abbott Phone: +61 8 9380 2734 School of Physics, M013 Fax: +61 8 9380 1014 The University of Western Australia (CRICOS Provider No 00126G) 35 Stirling Highway Crawley WA 6009 mailto:paul at physics.uwa.edu.au AUSTRALIA http://physics.uwa.edu.au/~paul