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Generalize variance to other types

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Josep Sanjuas 2015-04-18 13:28:48 +02:00
commit e76f54e059
1 changed files with 3 additions and 3 deletions
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lib/pure/math.nim
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@ -122,13 +122,13 @@ proc mean*[T](x: openArray[T]): float {.noSideEffect.} =
## ``toFloat(x: T): float`` must be defined. ## ``toFloat(x: T): float`` must be defined.
result = toFloat(sum(x)) / toFloat(len(x)) result = toFloat(sum(x)) / toFloat(len(x))
proc variance*(x: openArray[float]): float {.noSideEffect.} = proc variance*[T](x: openArray[T]): float {.noSideEffect.} =
## computes the variance of the elements in `x`. ## computes the variance of the elements in `x`.
## If `x` is empty, NaN is returned. ## If `x` is empty, NaN is returned.
result = 0.0 result = 0.0
var m = mean(x) var m = mean(x)
for i in 0 .. high(x): for i in items(x):
var diff = x[i] - m var diff = toFloat(i) - m
result = result + diff*diff result = result + diff*diff
result = result / toFloat(len(x)) result = result / toFloat(len(x))