FindFit

• To: mathgroup at smc.vnet.net
• Subject: [mg92733] FindFit
• From: Artur <grafix at csl.pl>
• Date: Sat, 11 Oct 2008 06:47:47 -0400 (EDT)
• References: <200810100835.EAA07169@smc.vnet.net>

```Dear Mathematica Gurus,
Who have idea which procedure I can use inspite FindFit in following:
In[1]: Table[Simplify[Expand[(1/2) ((1 + Sqrt[13])^(2^n) + (1 -
Sqrt[13])^(2^n))]], {n, 1, 6}]
Out[1]: {14, 248, 102272, 20489142272, 839425017825619607552,
1409268686920894404615927074915795024740352}
In[2]: FindFit[{14, 248, 102272, 20489142272, 839425017825619607552,
1409268686920894404615927074915795024740352}, (1/
2) ((a + Sqrt[b])^(2^x) + (a - Sqrt[b])^(2^x)), {a, b}, x,
WorkingPrecision -> 100]
Out[2]:{a -> 2.43785286368448657933626328600,
b -> 4.95343824602875750402007143975}

Should be: {a -> 1.00000000000000000000,
b -> 13.000000000000000000}

Who have idea how find (true) a,b when I have sequence
Best wishes
Artur

```

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