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FindFit bug

  • To: mathgroup at smc.vnet.net
  • Subject: [mg116055] FindFit bug
  • From: Igor <igor.volkov at gmail.com>
  • Date: Mon, 31 Jan 2011 03:23:20 -0500 (EST)

Hello,
It seems that FindFit cannot fit a sine function.
It produces no warnings and gives a totally
wrong answer:

dat = Table[{t, 3 Sin[3 t + 1]}, {t, -3, 3, 0.1}];

fit = FindFit[dat, a Sin[w t + f], {a, w, f}, t]

Show[ListPlot[dat], Plot[a Sin[w t + f] /. fit, {t, -3, 3}]]

Output: {a -> 0.599211, w -> 1.51494, f -> 3.80421}

At the same time it fits Sin[3t+1] just fine.


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