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moved error message sooner for invalid mean and stdev

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This commit is contained in:
Quinn Dougherty 2022-07-04 09:57:00 -04:00
parent 5b41019c04
commit 7a419742ad
1 changed files with 8 additions and 4 deletions
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12
packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
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@ -129,14 +129,18 @@ module Beta = {
// https://en.wikipedia.org/wiki/Beta_distribution#Mean_and_sample_size
let alpha = mean *. sampleSize
let beta = (1.0 -. mean) *. sampleSize
alpha->make(beta)
make(alpha, beta)
}
let fromMeanAndStdev = (mean, stdev) => {
// https://en.wikipedia.org/wiki/Beta_distribution#Mean_and_variance
let var = stdev *. stdev
let sampleSize = mean *. (1.0 -. mean) /. var -. 1.0
mean->fromMeanAndSampleSize(sampleSize)
if !(0.0 < stdev && stdev <= 0.5) || !(0.0 <= mean && mean <= 1.0) {
"Beta mean must be in [0,1] and stdev must be in (1,0.5]"->Error
} else {
let var = stdev *. stdev
let sampleSize = mean *. (1.0 -. mean) /. var -. 1.0
fromMeanAndSampleSize(mean, sampleSize)
}
}
}