[OT] fastest fibbonacci

[Era Scarecrow via Digitalmars-d]

On Monday, 24 October 2016 at 19:03:51 UTC, Era Scarecrow wrote:
> It's only good through 71 iterations (longs) then it starts 
> having errors. Also for some odd reason the input is one off, 
> so I had to add a -1 to the input for it to align. This makes 
> it accurate to 41/64 bit results.
>
> 71: 308061521170129     308061521170129 true
> 72: 498454011879264     498454011879265 false

  Hmm as an experiment I changed from doubles to reals, and got a 
slightly higher result, up to 85 giving us a 58/64

83: 99194853094755497   99194853094755497       true
84: 160500643816367088  160500643816367088      true
85: 259695496911122585  259695496911122585      true
86: 420196140727489673  420196140727489674      false
87: 679891637638612258  679891637638612259      false
88: 1100087778366101931 1100087778366101933     false