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ferret/pkg/stdlib/math/stddev_population.go
2018-10-14 13:06:27 -04:00

42 lines
909 B
Go

package math
import (
"context"
"math"
"github.com/MontFerret/ferret/pkg/runtime/core"
"github.com/MontFerret/ferret/pkg/runtime/values"
)
// StandardDeviationPopulation returns the population standard deviation of the values in a given array.
// @params (Array) - Array of numbers.
// @returns (Float) - The population standard deviation.
func StandardDeviationPopulation(_ context.Context, args ...core.Value) (core.Value, error) {
var err error
err = core.ValidateArgs(args, 1, 1)
if err != nil {
return values.None, err
}
err = core.ValidateType(args[0], core.ArrayType)
if err != nil {
return values.None, err
}
arr := args[0].(*values.Array)
if arr.Length() == 0 {
return values.NewFloat(math.NaN()), nil
}
vp, err := variance(arr, values.NewInt(0))
if err != nil {
return values.NewFloat(math.NaN()), err
}
return values.NewFloat(math.Pow(float64(vp), 0.5)), nil
}