Merge pull request #29 from observerly/feature/utilities/getNormalize…

…dInclinationDegree

feat: Added getNormalizedInclinationDegree() to utilities module in @observerly/astrometry.

src/utilities.ts

@@ -61,3 +61,39 @@ export const getNormalizedAzimuthalDegree = (degrees: number): number => {
 }
 
 /*****************************************************************************************************************/
+
+/**
+ *
+ * getNormalizedInclinationDegree()
+ *
+ * Normalizes an inclination angle it to a value between 0 and 360.
+ *
+ * @param degrees - The angle in degrees to convert.
+ * @returns The normalized angle in degrees.
+ *
+ */
+export const getNormalizedInclinationDegree = (degrees: number): number => {
+  let d = degrees
+
+  // Correct for angles greater than 90° or less than -90°
+  if (degrees > 90) {
+    d = 180 - degrees
+  }
+
+  // Correct for angles less than -90°
+  if (degrees < -90) {
+    d = -180 - degrees
+  }
+
+  if (d < 0) {
+    d % -90
+  }
+
+  if (d > 0) {
+    d % 90
+  }
+
+  return d
+}
+
+/*****************************************************************************************************************/

tests/utilities.spec.ts

@@ -13,7 +13,8 @@ import { describe, expect, it } from 'vitest'
 import {
   convertDegreesToRadians,
   convertRadiansToDegrees,
-  getNormalizedAzimuthalDegree
+  getNormalizedAzimuthalDegree,
+  getNormalizedInclinationDegree
 } from '../src/utilities'
 
 /*****************************************************************************************************************/
@@ -106,3 +107,44 @@ describe('getNormalizedAzimuthalDegree', () => {
 })
 
 /*****************************************************************************************************************/
+
+describe('getNormalizedInclinationDegree', () => {
+  it('should be defined', () => {
+    expect(getNormalizedInclinationDegree).toBeDefined()
+  })
+
+  it('should correctly normalize a degree value to between -90 and 90', () => {
+    let degree = getNormalizedInclinationDegree(91)
+    expect(degree).toBe(89)
+
+    degree = getNormalizedInclinationDegree(-91)
+    expect(degree).toBe(-89)
+
+    degree = getNormalizedInclinationDegree(0)
+    expect(degree).toBe(0)
+
+    degree = getNormalizedInclinationDegree(90)
+    expect(degree).toBe(90)
+
+    degree = getNormalizedInclinationDegree(-90)
+    expect(degree).toBe(-90)
+
+    degree = getNormalizedInclinationDegree(180)
+    expect(degree).toBe(0)
+
+    degree = getNormalizedInclinationDegree(-180)
+    expect(degree).toBe(0)
+
+    degree = getNormalizedInclinationDegree(270)
+    expect(degree).toBe(-90)
+
+    degree = getNormalizedInclinationDegree(-270)
+    expect(degree).toBe(90)
+
+    degree = getNormalizedInclinationDegree(120)
+    expect(degree).toBe(60)
+
+    degree = getNormalizedInclinationDegree(-130)
+    expect(degree).toBe(-50)
+  })
+})