|
|
A192040
|
|
Decimal approximation of x such that f(x)=7, where f is the Fibonacci function described in Comments.
|
|
1
|
|
|
5, 7, 2, 1, 4, 6, 1, 7, 3, 4, 9, 5, 3, 8, 6, 7, 5, 9, 6, 7, 4, 5, 2, 5, 4, 4, 3, 1, 4, 9, 3, 4, 9, 3, 9, 5, 8, 4, 2, 5, 7, 2, 7, 9, 6, 2, 3, 6, 6, 2, 8, 2, 2, 6, 1, 2, 6, 4, 5, 1, 8, 6, 7, 6, 9, 0, 5, 7, 0, 5, 4, 6, 7, 3, 3, 2, 8, 2, 9, 9, 6, 6, 7, 4, 6, 3, 2, 2, 1, 5, 1, 8, 5, 5, 9, 7, 0, 7, 1, 5
(list;
constant;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
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.
|
|
LINKS
|
|
|
EXAMPLE
|
5.721461734953867596745254431493493958425727962366282
|
|
MATHEMATICA
|
r = GoldenRatio; s = 1/Sqrt[5];
f[x_] := s (r^x - r^-x Cos[Pi x]);
x /. FindRoot[Fibonacci[x] == 7, {x, 5}, WorkingPrecision -> 100]
RealDigits[%, 10]
(Show[Plot[#1, #2], ListPlot[Table[{x, #1}, #2]]] &)[
Fibonacci[x], {x, -7, 7}]
|
|
CROSSREFS
|
|
|
KEYWORD
|
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|