Add inverse trigonometric functions (#31)

AlexanderTar · Jan 9, 2023 · d8d6a11 · d8d6a11
1 parent c43a567
commit d8d6a11
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diff --git a/Sources/MatrixTrigonometry.swift b/Sources/MatrixTrigonometry.swift
@@ -40,3 +40,32 @@ public func cos(_ A: Matrix) -> Matrix {
 public func tan(_ A: Matrix) -> Matrix {
     return matrixFunction(tan, A)
 }
+
+/// Return the arcsine of `A`, where return value is
+/// in the range -pi/2 to pi/2.
+///
+/// - Parameters
+///     - A: matrix
+/// - Returns: arcsine of a matrix values
+public func asin(_ A: Matrix) -> Matrix {
+    return matrixFunction(asin, A)
+}
+
+/// Return the arccosine of `A`, where return value is
+/// in the range 0 to pi.
+///
+/// - Parameters
+///     - A: matrix
+/// - Returns: arccosine of a matrix values
+public func acos(_ A: Matrix) -> Matrix {
+    return matrixFunction(acos, A)
+}
+
+/// Return the arctangent of `a`.
+///
+/// - Parameters
+///     - A: matrix
+/// - Returns: arctangent of a matrix values
+public func atan(_ A: Matrix) -> Matrix {
+    return matrixFunction(atan, A)
+}
diff --git a/Sources/VectorTrigonometry.swift b/Sources/VectorTrigonometry.swift
@@ -42,3 +42,32 @@ public func cos(_ a: Vector) -> Vector {
 public func tan(_ a: Vector) -> Vector {
     return vectorFunction(vvtan, a)
 }
+
+/// Return the arcsine of `a`, where return value is
+/// in the range -pi/2 to pi/2.
+///
+/// - Parameters
+///     - a: vector
+/// - Returns: arcsine of a vector values
+public func asin(_ a: Vector) -> Vector {
+    return vectorFunction(vvasin, a)
+}
+
+/// Return the arccosine of `a`, where return value is
+/// in the range 0 to pi.
+///
+/// - Parameters
+///     - a: vector
+/// - Returns: arccosine of a vector values
+public func acos(_ a: Vector) -> Vector {
+    return vectorFunction(vvacos, a)
+}
+
+/// Return the arctangent of `a`.
+///
+/// - Parameters
+///     - a: vector
+/// - Returns: arctangent of a vector values
+public func atan(_ a: Vector) -> Vector {
+    return vectorFunction(vvatan, a)
+}
diff --git a/Tests/MatrixTests.swift b/Tests/MatrixTests.swift
@@ -494,6 +494,21 @@ class MatrixSpec: QuickSpec {
                 let res = Matrix([[tan(1.0), tan(2.0)], [tan(3.0), tan(4.0)]])
                 expect(tan(m1)) == res
             }
+            it("asin") {
+                let m1 = Matrix([[0.5, -0.5], [1.0, -1.0]])
+                let res = Matrix([[asin(0.5), asin(-0.5)], [asin(1.0), asin(-1.0)]])
+                expect(asin(m1)) == res
+            }
+            it("acos") {
+                let m1 = Matrix([[0.5, -0.5], [1.0, -1.0]])
+                let res = Matrix([[acos(0.5), acos(-0.5)], [acos(1.0), acos(-1.0)]])
+                expect(acos(m1)) == res
+            }
+            it("atan") {
+                let m1 = Matrix([[1.0, 2.0], [3.0, 4.0]])
+                let res = Matrix([[atan(1.0), atan(2.0)], [atan(3.0), atan(4.0)]])
+                expect(atan(m1)) == res
+            }
         }
 
         describe("Matrix statistics tests") {

diff --git a/Tests/VectorTests.swift b/Tests/VectorTests.swift
@@ -245,6 +245,21 @@ class VectorSpec: QuickSpec {
                 let res = [tan(1.0), tan(2.0), tan(3.0)]
                 expect(tan(vec)).to(beCloseTo(res))
             }
+            it("asin") {
+                let vec = [1.0, 2.0, 3.0]
+                let res = [asin(1.0), asin(2.0), asin(3.0)]
+                expect(asin(vec)).to(beCloseTo(res))
+            }
+            it("acos") {
+                let vec = [1.0, 2.0, 3.0]
+                let res = [acos(1.0), acos(2.0), acos(3.0)]
+                expect(acos(vec)).to(beCloseTo(res))
+            }
+            it("atan") {
+                let vec = [1.0, 2.0, 3.0]
+                let res = [atan(1.0), atan(2.0), atan(3.0)]
+                expect(atan(vec)).to(beCloseTo(res))
+            }
         }
 
         describe("Vector statistics tests") {