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Re: FindFit

  • To: mathgroup at smc.vnet.net
  • Subject: [mg105812] Re: [mg105797] FindFit
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sun, 20 Dec 2009 06:53:46 -0500 (EST)
  • Reply-to: hanlonr at cox.net

data = {{40, 0.0624}, {50, 42.276}, {58, 127.718}, {60, 216.608}, {70, 
    2040.088}};

In the model, express the multiplier as an additive term in the exponent 

model1 = Exp[a + k*t];

model2 = Exp[a + k*t] + b;

fit = FindFit[data, #, {a, b, k}, t] & /@ {model1, model2}

{{a->-8.16007,b->1.,k->0.22544},{a->-8.44721,b->7.41933,k->0.22949}}

LogPlot[{
  Tooltip[model1 /. fit[[1]]],
  Tooltip[model2 /. fit[[2]]]}, {t, 40, 70},
 Epilog -> {Red, AbsolutePointSize[4],
   Point[{#[[1]], Log[#[[2]]]} & /@ data]}]


Bob Hanlon

---- jj <yohan2 at spray.se> wrote: 

=============
Can anybody help me?
I want to try to show my model (function) and my data in the same
graph so I can see that my conclusions are correct.
data= { {40,0.0624}, {50,42.2.276}, {58,127.718}, {60,216.608},
{70,2040.088},
I used FindFit for Exponential as my model to plot:
t200= {Exp200}

t200= {Exp300}

model=aExp[kt];

fit=FindFit[data,model,{a,k},t]

Best regads jj




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