Hi there! Are you asking about the math or about a programming strategy?
>From a programming point of view, you could use a vector of pre-computed Fibonacci numbers if the numbers you're dealing with aren't too big. Otherwise, I'd give a try to use the closed formula for Fibonacci numbers with SymPy's equation solver. Anyway, I suggest to ask about mathematical details on http://math.stackexchange.com/ On Friday, 8 April 2016 02:19:14 UTC+2, Amy Valhausen wrote: > > Fibonacci Reverse Calculation? > > Hi All! > > I was reading Dr Knotts entries about Binets formula on his fibonacci page > > http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/fibFormula.html > > I entered the formula into an Excel spreadsheet to see how this would work > ; > > Binet Formula > Fib(n) = (1.6180339^n – (–0.6180339..)^n) / 2.236067977.. > > Its fascinating to see how I can enter any number for (n) and see the > correct fibonacci number returned! > > I have a question though, I am a newbie computer programmer using > VB and Python and my math skills are average at best but I am very > interest and curious about math and especially fibonacci numbers! > > Say I wanted to reverse and change the process. > > I have a very large fibonacci number and I want to know what the > fibonacci number is at a specified position BEFORE it, how would > I compute this, what would the formula be? > > So for example I have the 301 st fibo number of ; > > 359579325206583560961765665172189099052367214309267232255589801 > > And I want to be able to find what the fibonacci value would be (n) numbers > BEFORE this... so I might want to know what the fibo value would be 50 > numbers before or the 251st fibo number. How would I do that? > > > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/5b6e68d0-8b65-495a-bd8b-0c601bdef403%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
