Re: How can I get the previous Fibonacci calculated

*To*: mathgroup at smc.vnet.net*Subject*: [mg100304] Re: [mg100266] How can I get the previous Fibonacci calculated*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 31 May 2009 06:36:51 -0400 (EDT)*Reply-to*: hanlonr at cox.net

prevFib[x_] := Module[{m, n, x2}, x2 = SetPrecision[x, 100]; If[x > 10^15, N[x/GoldenRatio], m = (n /. FindRoot[Fibonacci[n] - x2 == 0, {n, 100}, WorkingPrecision -> 100]) - 1; If[Abs[m - Round[m]] < 10^-10, Fibonacci[Round[m]], N[Fibonacci[m]]]]] prevFib[13] 8 prevFib[Fibonacci[50]] == Fibonacci[49] True prevFib[Fibonacci[10000]] == Fibonacci[9999] True prevFib[Fibonacci[20000]] == Fibonacci[19999] True prevFib[234.34*^10] 1.4483008492365037*^12 Bob Hanlon ---- ratulloch at gmail.com wrote: ============= Greetings How can I get a previous Fibonacci calculated number in a specific range. I can calculate the previous number of phi see below phi1 =(1+sqrt(5))/2 13/phi1 I tested it with 13 and got 8.034441857 .....so that works but how can I get only the previous numbers of Fibonacci in a specified range from 20 to 20000 if I input a large number like 234.34e10 tia sal2