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Introducing Angle type [Issue #88] #169

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b313290
Introduced Angle type [Issue #88]
jkalias Dec 8, 2020
c924790
Removed hyperbolic functions
jkalias Dec 8, 2020
437b280
cos(Angle) changed, 270deg stil not giving 0
jkalias Dec 9, 2020
bb19809
cos works for all cases
jkalias Dec 9, 2020
d4a4c3c
sin(Angle) also works as expected
jkalias Dec 9, 2020
f676bc1
removed newline
jkalias Dec 9, 2020
bb474f5
more tests for cos and sin
jkalias Dec 9, 2020
2fad678
cos and sin tests along the whole (-π,π) interval
jkalias Dec 9, 2020
4844b2a
tests and implementation for tan
jkalias Dec 9, 2020
c5828b8
Strict equality in tests, not approximate
jkalias Dec 9, 2020
2fba7c7
Removed conformance to BinaryFloatingPoint
jkalias Dec 13, 2020
79f5f7a
Added conformance to AdditiveArithmetic and other utilities
jkalias Dec 13, 2020
5f57416
Added AdditiveArithmetic tests
jkalias Dec 13, 2020
e09ef7a
Fixed conformance to Equatable, and added range containment functions…
jkalias Dec 14, 2020
131774a
Updated public access modifier style
jkalias Dec 14, 2020
949c9a2
Refactored AngleTests
jkalias Dec 16, 2020
63bdaaf
cos and sin for exact degrees
jkalias Dec 18, 2020
acd67fb
exact tan implemented
jkalias Dec 18, 2020
14c520b
inverse trigonometric functions fixed
jkalias Dec 19, 2020
9e7fb84
range containment and distance checks
jkalias Dec 20, 2020
1743914
documentation
jkalias Dec 20, 2020
56c5ffc
Angle type with trig-pi branch (#85)
jkalias Mar 21, 2021
83ba41b
Merge branch 'main' into angle-type
jkalias Mar 18, 2022
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31 changes: 27 additions & 4 deletions Sources/RealModule/Angle.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@
///
/// All trigonometric functions expect the argument to be passed as radians (Real), but this is not enforced by the type system.
/// This type serves exactly this purpose, and can be seen as an alternative to the underlying Real implementation.
public struct Angle<T: Real> {
public struct Angle<T: Real>: Equatable {
public var radians: T
public init(radians: T) { self.radians = radians }
public static func radians(_ val: T) -> Angle<T> { .init(radians: val) }
Expand Down Expand Up @@ -160,9 +160,32 @@ public extension Angle {
}
}

extension Angle: Equatable {
public static func == (lhs: Angle<T>, rhs: Angle<T>) -> Bool {
lhs.radians.isApproximatelyEqual(to: rhs.radians)
public extension Angle {
/// Checks whether the current angle is contained within a given closed range.
///
/// - Parameters:
///
/// - range: The closed angular range within which containment is checked.
func contained(in range: ClosedRange<Angle<T>>) -> Bool {
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@xwu xwu Dec 14, 2020 •
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What is the value of these APIs over what's written in the body? I would suggest not including these separately; the existing forms are canonical and straightforward enough to write.

What @NevinBR is getting at, I think, is that 361 degrees is contained "between" 0 degrees and 2 degrees. This does not offer that functionality, and convenient access to it would be useful. It would need to be distinguished from the functionality here, though, through some thoughtful naming.

For API naming purposes, incidentally, the function would need to be named isContained; and for style purposes, the access modifier public should be specified on each member (and therefore is not necessary on the extension itself).

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What @NevinBR is getting at, I think, is that 361 degrees is contained "between" 0 degrees and 2 degrees. This does not offer that functionality.

Additionally, 175º and -175º are both “between” 170º and -170º (but they are not between -170º and 170º).

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@jkalias jkalias Dec 14, 2020 •
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So, essentially you mean @NevinBR that the containment should be performed on the normalized angular range, right?

361º -> normalized to 1º -> contained in -10º...10º
361º -> normalized to 1º -> not contained in 10º...-10º
175º -> normalized to 175º -> contained in -170º...170º
-175º -> normalized to -175º -> contained in -170º...170º
175º -> normalized to 175º -> not contained in 170º...-170º
-175º -> normalized to -175º -> not contained in 170º...-170º

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I’m not entirely sure how normalization should come into play. Probably yes normalized angles should be used for comparison / containment, and if someone wants to work with the unnormalized value they can extract it and do so manually.

However, several of your examples do not behave as I would expect:

175º -> normalized to 175º -> contained in -170º...170º
-175º -> normalized to -175º -> contained in -170º...170º
175º -> normalized to 175º -> not contained in 170º...-170º
-175º -> normalized to -175º -> not contained in 170º...-170º

These should be:

175º -> normalized to 175º -> not contained in -170º...170º
-175º -> normalized to -175º -> not contained in -170º...170º
175º -> normalized to 175º -> yes contained in 170º...-170º
-175º -> normalized to -175º -> yes contained in 170º...-170º

range.contains(self)
}

/// Checks whether the current angle is contained within a given half-open range.
///
/// - Parameters:
///
/// - range: The half-open angular range within which containment is checked.
func contained(in range: Range<Angle<T>>) -> Bool {
range.contains(self)
}
}

extension Angle: Comparable {
public static func < (lhs: Angle<T>, rhs: Angle<T>) -> Bool {
guard lhs != rhs else {
return false
}
return lhs.radians < rhs.radians
}
}

Expand Down
20 changes: 18 additions & 2 deletions Tests/RealTests/AngleTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -107,8 +107,8 @@ where Self: BinaryFloatingPoint {

static func additiveArithmeticTests() {
var angle = Angle(degrees: 30)
XCTAssertEqual(Angle(degrees: 50), angle + Angle(degrees: 20))
XCTAssertEqual(Angle(degrees: 10), angle - Angle(degrees: 20))
assertClose(50, (angle + Angle(degrees: 20)).degrees)
assertClose(10, (angle - Angle(degrees: 20)).degrees)
XCTAssertEqual(Angle(degrees: 60), angle * 2)
XCTAssertEqual(Angle(degrees: 60), 2 * angle)
XCTAssertEqual(Angle(degrees: 15), angle / 2)
Expand All @@ -121,6 +121,18 @@ where Self: BinaryFloatingPoint {
angle /= 6
XCTAssertEqual(Angle(degrees: 10), angle)
}

static func rangeContainmentTests() {
let angle = Angle(degrees: 30)
XCTAssertTrue(angle.contained(in: Angle(degrees: 10)...Angle(degrees: 40)))
XCTAssertTrue(angle.contained(in: Angle(degrees: 10)...Angle(degrees: 30)))
XCTAssertTrue(angle.contained(in: Angle(degrees: 30)...Angle(degrees: 40)))
XCTAssertFalse(angle.contained(in: Angle(degrees: 10)...Angle(degrees: 20)))
XCTAssertFalse(angle.contained(in: Angle(degrees: 50)...Angle(degrees: 60)))
XCTAssertTrue(angle.contained(in: Angle(degrees: 30)..<Angle(degrees: 40)))
XCTAssertFalse(angle.contained(in: Angle(degrees: 10)..<Angle(degrees: 30)))
XCTAssertTrue(angle.contained(in: Angle(degrees: 10)..<Angle(degrees: 40)))
}
}

final class AngleTests: XCTestCase {
Expand All @@ -131,6 +143,7 @@ final class AngleTests: XCTestCase {
Float16.trigonometricFunctionChecks()
Float16.specialDegreesTrigonometricFunctionChecks()
Float16.additiveArithmeticTests()
Float16.rangeContainmentTests()
}
}
#endif
Expand All @@ -140,13 +153,15 @@ final class AngleTests: XCTestCase {
Float.trigonometricFunctionChecks()
Float.specialDegreesTrigonometricFunctionChecks()
Float.additiveArithmeticTests()
Float.rangeContainmentTests()
}

func testDouble() {
Double.conversionBetweenRadiansAndDegreesChecks()
Double.trigonometricFunctionChecks()
Double.specialDegreesTrigonometricFunctionChecks()
Double.additiveArithmeticTests()
Double.rangeContainmentTests()
}

#if (arch(i386) || arch(x86_64)) && !os(Windows) && !os(Android)
Expand All @@ -155,6 +170,7 @@ final class AngleTests: XCTestCase {
Float80.trigonometricFunctionChecks()
Float80.specialDegreesTrigonometricFunctionChecks()
Float80.additiveArithmeticTests()
Float80.rangeContainmentTests()
}
#endif
}