RosettaCodeData/Task/Numeric-error-propagation/Swift/numeric-error-propagation.s...

75 lines
2.3 KiB
Swift

import Foundation
precedencegroup ExponentiationGroup {
higherThan: MultiplicationPrecedence
}
infix operator ** : ExponentiationGroup
infix operator ±
func ±(_ lhs: Double, _ rhs: Double) -> UncertainDouble { UncertainDouble(value: lhs, error: rhs) }
struct UncertainDouble {
var value: Double
var error: Double
static func +(_ lhs: UncertainDouble, _ rhs: UncertainDouble) -> UncertainDouble {
return UncertainDouble(value: lhs.value + rhs.value, error: pow(pow(lhs.error, 2) + pow(rhs.error, 2), 0.5))
}
static func +(_ lhs: UncertainDouble, _ rhs: Double) -> UncertainDouble {
return UncertainDouble(value: lhs.value + rhs, error: lhs.error)
}
static func -(_ lhs: UncertainDouble, _ rhs: UncertainDouble) -> UncertainDouble {
return UncertainDouble(value: lhs.value - rhs.value, error: pow(pow(lhs.error, 2) + pow(rhs.error, 2), 0.5))
}
static func -(_ lhs: UncertainDouble, _ rhs: Double) -> UncertainDouble {
return UncertainDouble(value: lhs.value - rhs, error: lhs.error)
}
static func *(_ lhs: UncertainDouble, _ rhs: UncertainDouble) -> UncertainDouble {
let val = lhs.value * rhs.value
return UncertainDouble(
value: val,
error: pow(pow(val, 2) * (pow(lhs.error / lhs.value, 2) + pow(rhs.error / rhs.value, 2)), 0.5)
)
}
static func *(_ lhs: UncertainDouble, _ rhs: Double) -> UncertainDouble {
return UncertainDouble(value: lhs.value * rhs, error: abs(lhs.error * rhs))
}
static func /(_ lhs: UncertainDouble, _ rhs: UncertainDouble) -> UncertainDouble {
let val = lhs.value / rhs.value
return UncertainDouble(
value: val,
error: pow(val, 2) * (pow(lhs.error / lhs.value, 2) + pow(rhs.error / rhs.value, 2))
)
}
static func /(_ lhs: UncertainDouble, _ rhs: Double) -> UncertainDouble {
return UncertainDouble(value: lhs.value / rhs, error: abs(lhs.error * rhs))
}
static func **(_ lhs: UncertainDouble, _ power: Double) -> UncertainDouble {
let val = pow(lhs.value, power)
return UncertainDouble(value: val, error: abs((val * power) * (lhs.error / lhs.value)))
}
}
extension UncertainDouble: CustomStringConvertible {
public var description: String { "\(value) ± \(error)" }
}
let (x1, y1) = (100 ± 1.1, 50 ± 1.2)
let (x2, y2) = (200 ± 2.2, 100 ± 2.3)
let d = ((x2 - x1) ** 2 + (y2 - y1) ** 2) ** 0.5
print(d)