ootk-core/src/transforms/conversions.ts

Orbital Object Toolkit. A modern typed replacement for satellite.js including SGP4 propagation, TLE parsing, Sun and Moon calculations, and more.

/**
 * @author Theodore Kruczek.
 * @license MIT
 * @copyright (c) 2022-2025 Theodore Kruczek Permission is
 * hereby granted, free of charge, to any person obtaining a copy of this
 * software and associated documentation files (the "Software"), to deal in the
 * Software without restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

import { DEG2RAD, Degrees, PI, RAD2DEG, Radians } from '../main.js';

/**
 * Converts radians to degrees.
 * @param radians The value in radians to be converted.
 * @returns The value in degrees.
 */
export function rad2deg(radians: Radians): Degrees {
  return <Degrees>((radians * 180) / PI);
}

/**
 * Converts degrees to radians.
 * @param degrees The value in degrees to be converted.
 * @returns The value in radians.
 */
export function deg2rad(degrees: Degrees): Radians {
  return <Radians>((degrees * PI) / 180.0);
}

/**
 * Converts radians to degrees latitude.
 * @param radians The radians value to convert.
 * @returns The corresponding degrees latitude.
 * @throws RangeError if the radians value is outside the range [-PI/2; PI/2].
 */
export function getDegLat(radians: Radians): Degrees {
  if (radians < -PI / 2 || radians > PI / 2) {
    throw new RangeError('Latitude radians must be in range [-PI/2; PI/2].');
  }

  return (radians * RAD2DEG) as Degrees;
}

/**
 * Converts radians to degrees for longitude.
 * @param radians The value in radians to be converted.
 * @returns The converted value in degrees.
 * @throws {RangeError} If the input radians is not within the range [-PI; PI].
 */
export function getDegLon(radians: Radians): Degrees {
  if (radians < -PI || radians > PI) {
    throw new RangeError('Longitude radians must be in range [-PI; PI].');
  }

  return (radians * RAD2DEG) as Degrees;
}

/**
 * Converts degrees to radians for latitude.
 * @param degrees The degrees value to convert.
 * @returns The equivalent radians value.
 * @throws {RangeError} If the degrees value is not within the range [-90, 90].
 */
export function getRadLat(degrees: Degrees): Radians {
  if (degrees < -90 || degrees > 90) {
    throw new RangeError('Latitude degrees must be in range [-90; 90].');
  }

  return (degrees * DEG2RAD) as Radians;
}

/**
 * Converts degrees to radians.
 * @param degrees The value in degrees to be converted.
 * @returns The value in radians.
 * @throws {RangeError} If the input degrees are not within the range [-180; 180].
 */
export function getRadLon(degrees: Degrees): Radians {
  if (degrees < -180 || degrees > 180) {
    throw new RangeError('Longitude degrees must be in range [-180; 180].');
  }

  return (degrees * DEG2RAD) as Radians;
}