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-- fibonacci function with cache
-- very inefficient fibonacci function
function fib(n)
N=N+1
if n<2 then
return n
else
return fib(n-1)+fib(n-2)
end
end
-- a general-purpose value cache
function cache(f)
local c={}
return function (x)
local y=c[x]
if not y then
y=f(x)
c[x]=y
end
return y
end
end
-- run and time it
function test(s,f)
N=0
local c=os.clock()
local v=f(n)
local t=os.clock()-c
print(s,n,v,t,N)
end
n=arg[1] or 24 -- for other values, do lua fib.lua XX
n=tonumber(n)
print("","n","value","time","evals")
test("plain",fib)
fib=cache(fib)
test("cached",fib)
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