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 Author Comment/Response Sabah 02/20/07 9:44pm Dear sir/madam I have a problem with nolinearfit, as I have wrote this program to evaluate the goodness of the fit, Start of the program \$DefaultFont = {"Courier", 16} (*1/6 SW APW 420.R3 *)     fa = 96519; r = 8.314472; t = 300.0; np1 = 16; z = 1; n = 2*10^-8; vp = -0.1; ki = 65; ke = 2; vcrd = List[-260, -240, -220, -200, -180, -160, -140, -120, -100, -80, -60, \ -40, -20, 0, 20, 40]; vcrd = vcrd/1000.0; icrd = List[-1119.401111, -854.4968, -705.1557692, -521.4944444, \ -372.1723333, -197.4627586, -44.48241379, 107.119655172414, 253.796666666667, 420.755357142857, 558.491071428571, 814.4564, 1208.03894736842, 1290.25578947368, 1776.5075, 2280.2]; icrd = icrd/1000.0; tbl1 = Table[{Part[vcrd, i], Part[icrd, i]}, {i, 1, np1}]; ivpt1 = ListPlot[%, PlotStyle -> {GrayLevel[0.4], AbsolutePointSize[8.5]}] il1 = Function[x, gl1*(x - vp)] ip = Function[x, z*fa*n*((k1*Exp[(z*x*fa)/(2*r*t)])* ka2 - (k2*Exp[-(z*x*fa/(2*r*t))])*ka1)/ ((k1*Exp[(z*x*fa)/(2*r*t)]) + (k2*Exp[-(z*x*fa/(2*r*t))]) + ka1 + ka2)] po = Function[x, (1/(1 + Exp[-(zgo*fa*(x - xho))/(r*t)]))] orc = Function[x, ((( po[x]*npo*fa^2*x)/(r*t))*( ki - ke*Exp[-(x*fa)/(r*t)]))/(1 - Exp[-(fa*x)/(r*t)])] pi = Function[x, 1 - (1/(1 + Exp[-(zgi*fa*(x - xhi))/(r*t)]))] irc = Function[x, (((pi[x]*npi*fa^2*x)/(r*t))*(ki - ke*Exp[-(x* fa)/(r*t)]))/(1 - Exp[-(fa*x)/(r*t)])] itot = Function[x, il1[x] + ip[x] + irc[x] + orc[x]] << Statistics`NonlinearFit` Options[NonlinearFit] f1 = NonlinearFit[tbl1, itot[x], {x}, {{ gl1, 6.3}, {k1, 4500.}, {k2, 0.5}, {ka1, 0.5}, {ka2, 180.}}] f2 = Plot[%, {x, -0.250, 0.05}] Show[f2, ivpt1] NonlinearRegress[tbl1, itot[x], {x}, {{ gl1, 6.3}, {k1, 4500.}, {k2, 0.5}, {ka1, 0.5}, \ {ka2, 180.}}, RegressionReport -> {ANOVATable, AsymptoticCorrelationMatrix, \ AsymptoticCovarianceMatrix, BestFit, BestFitParameters, EstimatedVarianceFitCurvatureTable, FitResiduals, HatDiagonal, \ MeanPredictionCITable, ParameterBias, ParameterConfidenceRegion, \ ParameterCITable, ParameterTable, PredictedResponse, SinglePredictionCITable, \ StartingParameters, StandardizedResiduals, SummaryReport}] End of the program it seems that the program worked with first two terms of the model but when I add the third and fourth terms the troubles started,this is the model itot = Function[x, il1[x] + ip[x] + irc[x] + orc[x]] Then if I used different data, I encountered with many problems, any one can help with mattar, please Thank you very much Best regard Sabah In URL: ,

 Thread 'Nonlinearfit' is now CLOSED Author Date Posted Nonlinearfit Sabah 02/20/07 9:44pm Re: Nonlinearfit Forum Modera... 02/28/07 10:50am Re: Nonlinearfit Sabah 02/28/07 8:05pm
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