Hello! I was following a tutorial on Bayesian inference and tried to implement the example given in nim. During that I found out that the first execution after compilation takes a lot longer than the following executions. Can someone explain me why?
Here are the timing result:
And here is the code i used:
import random, sequtils,future, times, os, strutils
template benchmark(benchmarkName: string, code: untyped) =
let t0 = epochTime()
code
let elapsed = epochTime() - t0
let elapsedStr = elapsed.formatFloat(format = ffDecimal, precision = 5)
echo "CPU Time [", benchmarkName, "] ", elapsedStr, "s"
benchmark "Total":
proc sampler(param:float): auto =
iterator sample (): float {.closure.} =
while true:
if rand(1.0) < param:
yield 1.0
else:
yield 0.0
return sample
proc take[T](iter: iterator():T,n:int): seq[T] =
result = newSeq[T](n)
for i in 0..<n:
result[i] = iter()
proc genModel(param: float):float =
result = 0.0
for e in sampler(param).take(16):
result += e
result = result/16.0
proc samplePrior():float =
rand(1.0)
proc bin[T](xs,ys:openArray[T],nBins:int,associatedX: float = 0.0): auto =
result = newSeq[tuple[x:T,count:int]](0)
let
leftBound = min(xs)
rightBound = max(xs)
dx = (rightBound-leftBound)/nBins.toFloat
for i in 1..<nBins:
let j = i.toFloat
result.add (leftBound + (j+associatedX)*dx,len(filter(xs, x => (leftBound + j*dx)<= x and x < (leftBound + (j+1)*dx))))
const data = 6/16
const nSamples = 100_000
var sampling: array[nSamples,tuple[param:float,result:float]]
benchmark "Sampeling":
for i in 0..<nSamples:
let tmp = samplePrior()
sampling[i] = (tmp, genModel(tmp))
benchmark "Filtering":
let filteredData = filter(sampling, t => t.result == data)
benchmark "Binning":
let binnedData = bin(map(filteredData, t => t.param), map(filteredData, t => t.result), 20)
benchmark "Totaling":
let total = foldl(map(binnedData, t => t.count), a+b)
benchmark "Posterior":
let posterior = map(binnedData, t => (x: t.x, prob: t.count/total))
Active Antivir?
: Active Antivir?
Only windows defender
I disabled windows defender, compiled and ran the executable two times and the speed was the same. Thank you for the help!