UnitsConverter.java

  1. /* Copyright 2002-2024 CS GROUP
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.utils.units;

  19. import org.orekit.errors.OrekitException;
  20. import org.orekit.errors.OrekitMessages;

  22. /** Converter between units.
  23.  * <p>
  24.  * Instances of this class are immutable.
  25.  * </p>
  26.  * @author Luc Maisonobe
  27.  * @since 11.0
  28.  */
  29. public class UnitsConverter {

  31.     /** Identity converter. */
  32.     public static final UnitsConverter IDENTITY =
  33.                     new UnitsConverter(Unit.ONE, Unit.ONE);

  35.     /** Percents to units converter. */
  36.     public static final UnitsConverter PERCENTS_TO_UNIT =
  37.                     new UnitsConverter(Unit.PERCENT, Unit.ONE);

  39.     /** Arcseconds to radians converter. */
  40.     public static final UnitsConverter ARC_SECONDS_TO_RADIANS =
  41.                     new UnitsConverter(Unit.parse("as"), Unit.RADIAN);

  43.     /** Milli arcseconds to radians converter. */
  44.     public static final UnitsConverter MILLI_ARC_SECONDS_TO_RADIANS =
  45.                     new UnitsConverter(Unit.parse("mas"), Unit.RADIAN);

  47.     /** Milli seconds to seconds converter. */
  48.     public static final UnitsConverter MILLI_SECONDS_TO_SECONDS =
  49.                     new UnitsConverter(Unit.parse("ms"), Unit.SECOND);

  51.     /** Nano Teslas to Tesla converter. */
  52.     public static final UnitsConverter NANO_TESLAS_TO_TESLAS =
  53.                     new UnitsConverter(Unit.parse("nT"), Unit.TESLA);

  55.     /** Days to seconds converter. */
  56.     public static final UnitsConverter DAYS_TO_SECONDS =
  57.                     new UnitsConverter(Unit.DAY, Unit.SECOND);

  59.     /** Kilometres to metres converter. */
  60.     public static final UnitsConverter KILOMETRES_TO_METRES =
  61.                     new UnitsConverter(Unit.KILOMETRE, Unit.METRE);

  63.     /** Square kilometres to square metres converter. */
  64.     public static final UnitsConverter KILOMETRES_2_TO_METRES_2 =
  65.                     new UnitsConverter(Unit.parse("km²"), Unit.parse("m²"));

  67.     /** km³/s² to m³/s² converter. */
  68.     public static final UnitsConverter KM3_P_S2_TO_M3_P_S2 =
  69.                     new UnitsConverter(Unit.parse("km³/s²"), Unit.parse("m³/s²"));

  71.     /** Source unit. */
  72.     private final Unit from;

  74.     /** Destination unit. */
  75.     private final Unit to;

  77.     /** Conversion factor. */
  78.     private final double factor;

  80.     /** Simple constructor.
  81.      * @param from source unit
  82.      * @param to destination unit
  83.      */
  84.     public UnitsConverter(final Unit from, final Unit to) {
  85.         this.from = from;
  86.         this.to   = to;
  87.         if (!from.sameDimension(to)) {
  88.             throw new OrekitException(OrekitMessages.INCOMPATIBLE_UNITS,
  89.                                       from.getName(), to.getName());
  90.         }
  91.         this.factor = from.getScale() / to.getScale();
  92.     }

  94.     /** Get the source unit.
  95.      * @return source unit
  96.      */
  97.     public Unit getFrom() {
  98.         return from;
  99.     }

  101.     /** Get the destination unit.
  102.      * @return destination unit
  103.      */
  104.     public Unit getTo() {
  105.         return to;
  106.     }

  108.     /** Convert a value.
  109.      * @param value value in the {@link #getFrom() source unit}
  110.      * @return value converted in the {@link #getTo() destination unit}
  111.      */
  112.     public double convert(final double value) {
  113.         return factor * value;
  114.     }

  116.     /** {@inheritDoc} */
  117.     @Override
  118.     public String toString() {
  119.         return from.getName() + " → " + to.getName();
  120.     }

  122. }
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