feat: Audit SymbolicDist.res
- Fix buggy lognormal multiplication code - Add precision to 90% confidence intervals code - Simplified lognormal code - Added sources for many of the manipulations
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@ -11,7 +11,7 @@ module Normal = {
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let from90PercentCI = (low, high) => {
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let from90PercentCI = (low, high) => {
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let mean = E.A.Floats.mean([low, high])
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let mean = E.A.Floats.mean([low, high])
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let stdev = (high -. low) /. (2. *. 1.644854)
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let stdev = (high -. low) /. (2. *. 1.6448536269514722)
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#Normal({mean: mean, stdev: stdev})
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#Normal({mean: mean, stdev: stdev})
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}
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}
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let inv = (p, t: t) => Jstat.Normal.inv(p, t.mean, t.stdev)
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let inv = (p, t: t) => Jstat.Normal.inv(p, t.mean, t.stdev)
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@ -19,14 +19,14 @@ module Normal = {
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let mean = (t: t) => Ok(Jstat.Normal.mean(t.mean, t.stdev))
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let mean = (t: t) => Ok(Jstat.Normal.mean(t.mean, t.stdev))
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let toString = ({mean, stdev}: t) => j`Normal($mean,$stdev)`
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let toString = ({mean, stdev}: t) => j`Normal($mean,$stdev)`
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let add = (n1: t, n2: t) => {
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let add = (n1: t, n2: t) => {
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let mean = n1.mean +. n2.mean
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let mean = n1.mean +. n2.mean
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let stdev = sqrt(n1.stdev ** 2. +. n2.stdev ** 2.)
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let stdev = Js.Math.sqrt(n1.stdev ** 2. +. n2.stdev ** 2.)
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#Normal({mean: mean, stdev: stdev})
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#Normal({mean: mean, stdev: stdev})
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}
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}
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let subtract = (n1: t, n2: t) => {
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let subtract = (n1: t, n2: t) => {
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let mean = n1.mean -. n2.mean
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let mean = n1.mean -. n2.mean
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let stdev = sqrt(n1.stdev ** 2. +. n2.stdev ** 2.)
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let stdev = Js.Math.sqrt(n1.stdev ** 2. +. n2.stdev ** 2.)
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#Normal({mean: mean, stdev: stdev})
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#Normal({mean: mean, stdev: stdev})
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}
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}
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@ -115,19 +115,22 @@ module Lognormal = {
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let mean = (t: t) => Ok(Jstat.Lognormal.mean(t.mu, t.sigma))
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let mean = (t: t) => Ok(Jstat.Lognormal.mean(t.mu, t.sigma))
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let sample = (t: t) => Jstat.Lognormal.sample(t.mu, t.sigma)
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let sample = (t: t) => Jstat.Lognormal.sample(t.mu, t.sigma)
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let toString = ({mu, sigma}: t) => j`Lognormal($mu,$sigma)`
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let toString = ({mu, sigma}: t) => j`Lognormal($mu,$sigma)`
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let from90PercentCI = (low, high) => {
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let from90PercentCI = (low, high) => {
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let logLow = Js.Math.log(low)
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let logLow = Js.Math.log(low)
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let logHigh = Js.Math.log(high)
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let logHigh = Js.Math.log(high)
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let mu = E.A.Floats.mean([logLow, logHigh])
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let mu = E.A.Floats.mean([logLow, logHigh])
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let sigma = (logHigh -. logLow) /. (2.0 *. 1.645)
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let sigma = (logHigh -. logLow) /. (2.0 *. 1.6448536269514722)
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#Lognormal({mu: mu, sigma: sigma})
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#Lognormal({mu: mu, sigma: sigma})
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}
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}
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let fromMeanAndStdev = (mean, stdev) => {
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let fromMeanAndStdev = (mean, stdev) => {
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// https://math.stackexchange.com/questions/2501783/parameters-of-a-lognormal-distribution
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// https://wikiless.org/wiki/Log-normal_distribution?lang=en#Generation_and_parameters
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if stdev > 0.0 {
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if stdev > 0.0 {
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let variance = Js.Math.pow_float(~base=stdev, ~exp=2.0)
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let variance = stdev ** 2.
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let meanSquared = Js.Math.pow_float(~base=mean, ~exp=2.0)
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let meanSquared = mean ** 2.
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let mu = Js.Math.log(mean) -. 0.5 *. Js.Math.log(variance /. meanSquared +. 1.0)
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let mu = 2*Js.Math.log(mean) -. 0.5 *. Js.Math.log(variance +. meanSquared)
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let sigma = Js.Math.pow_float(~base=Js.Math.log(variance /. meanSquared +. 1.0), ~exp=0.5)
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let sigma = Js.Math.sqrt(Js.Math.log((variance /. meanSquared) +. 1) )
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Ok(#Lognormal({mu: mu, sigma: sigma}))
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Ok(#Lognormal({mu: mu, sigma: sigma}))
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} else {
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} else {
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Error("Lognormal standard deviation must be larger than 0")
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Error("Lognormal standard deviation must be larger than 0")
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@ -135,10 +138,11 @@ module Lognormal = {
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}
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}
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let multiply = (l1, l2) => {
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let multiply = (l1, l2) => {
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// https://wikiless.org/wiki/Log-normal_distribution?lang=en#Multiplication_and_division_of_independent,_log-normal_random_variables
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let mu = l1.mu +. l2.mu
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let mu = l1.mu +. l2.mu
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let sigma = l1.sigma +. l2.sigma
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let sigma = Math.sqrt(l1.sigma ** 2. +. l2.sigma ** 2.)
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#Lognormal({mu: mu, sigma: sigma})
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#Lognormal({mu: mu, sigma: sigma})
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}
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}
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let divide = (l1, l2) => {
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let divide = (l1, l2) => {
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let mu = l1.mu -. l2.mu
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let mu = l1.mu -. l2.mu
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// We believe the ratiands will have covariance zero.
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// We believe the ratiands will have covariance zero.
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