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A192042
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Decimal approximation of x such that f(x)=3/2, where f is the Fibonacci function described in Comments.
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1
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2, 5, 0, 9, 3, 9, 4, 9, 1, 6, 3, 5, 4, 6, 8, 7, 0, 9, 2, 0, 5, 6, 3, 8, 9, 8, 4, 4, 6, 7, 9, 3, 5, 1, 3, 0, 1, 4, 8, 6, 9, 0, 7, 4, 1, 4, 9, 8, 4, 5, 1, 3, 2, 1, 2, 5, 3, 4, 6, 4, 1, 4, 7, 3, 9, 7, 3, 7, 7, 2, 3, 2, 1, 8, 8, 8, 8, 4, 0, 1, 1, 2, 1, 8, 1, 8, 9, 7, 5, 9, 4, 8, 7, 1, 6, 7, 3, 2, 4, 0
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OFFSET
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1,1
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COMMENTS
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f(x)=(r^x-r^(-x*cos[pi*x]))/sqrt(5), where r=(golden ratio)=(1+sqrt(5))/2. This function, a variant of the Binet formula, gives Fibonacci numbers for integer values of x; e.g., f(3)=2, f(4)=3, f(5)=5.
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LINKS
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EXAMPLE
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2.50939491635468709205638984467935130148690741498451
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MATHEMATICA
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r = GoldenRatio; s = 1/Sqrt[5];
f[x_] := s (r^x - r^-x Cos[Pi x]);
x /. FindRoot[Fibonacci[x] == 3/2, {x, 5}, WorkingPrecision -> 100]
RealDigits[%, 10]
(Show[Plot[#1, #2], ListPlot[Table[{x, #1}, #2]]] &)[
Fibonacci[x], {x, -7, 7}]
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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