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Numeric error propagation: Difference between revisions
Scala version
(Kotlin: fields renamed, new constructor) |
(Scala version) |
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puts ((x1 - x2) ** 2 + (y1 - y2) ** 2).sqrt</lang>
{{out]]
<pre>111.803398874989 ± 2.48716706314634</pre>
=={{header|Scala}}==
{{trans|Kotlin}}
<lang scala>import java.lang.Math._
class Approx(val ν: Double, val σ: Double = 0.0) {
def this(a: Approx) = this(a.ν, a.σ)
def this(n: Number) = this(n.doubleValue(), 0.0)
override def toString = s"$ν ±$σ"
def +(a: Approx) = Approx(ν + a.ν, sqrt(σ * σ + a.σ * a.σ))
def +(d: Double) = Approx(ν + d, σ)
def -(a: Approx) = Approx(ν - a.ν, sqrt(σ * σ + a.σ * a.σ))
def -(d: Double) = Approx(ν - d, σ)
def *(a: Approx) = {
val v = ν * a.ν
new Approx(v, sqrt(v * v * σ * σ / (ν * ν) + a.σ * a.σ / (a.ν * a.ν)))
}
def *(d: Double) = Approx(ν * d, abs(d * σ))
def /(a: Approx) = {
val t = ν / a.ν
Approx(t, sqrt(t * t * σ * σ / (ν * ν) + a.σ * a.σ / (a.ν * a.ν)))
}
def /(d: Double) = Approx(ν / d, abs(d * σ))
def ^(d: Double) = {
val t = pow(ν, d)
Approx(t, abs(t * d * σ / ν))
}
}
object Approx { def apply(ν: Double, σ: Double = 0.0) = new Approx(ν, σ) }
object NumericError extends App {
val x1 = Approx(100.0, 1.1)
val x2 = Approx(50.0, 1.2)
val y1 = Approx(200.0, 2.2)
val y2 = Approx(100.0, 2.3)
println((((x1 - x2)^2.0) + ((y1 - y2)^2.0))^0.5) // => 111.80339887498948 ±2.938366893361004
}</lang>
{{out}}
<pre>111.80339887498948 ±2.938366893361004</pre>
=={{header|Tcl}}==
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