1 package org.djunits.quantity;
2
3 import org.djunits.quantity.def.Quantity;
4 import org.djunits.unit.AbstractUnit;
5 import org.djunits.unit.UnitRuntimeException;
6 import org.djunits.unit.Unitless;
7 import org.djunits.unit.Units;
8 import org.djunits.unit.scale.LinearScale;
9 import org.djunits.unit.scale.Scale;
10 import org.djunits.unit.si.SIUnit;
11 import org.djunits.unit.system.UnitSystem;
12
13 /**
14 * Frequency encodes the number of events per unit of duration.
15 * <p>
16 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
17 * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
18 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
19 * @author Alexander Verbraeck
20 */
21 public class Frequency extends Quantity<Frequency>
22 {
23 /** Constant with value zero. */
24 public static final Frequency ZERO = Frequency.ofSi(0.0);
25
26 /** Constant with value one. */
27 public static final Frequency ONE = Frequency.ofSi(1.0);
28
29 /** Constant with value NaN. */
30 @SuppressWarnings("checkstyle:constantname")
31 public static final Frequency NaN = Frequency.ofSi(Double.NaN);
32
33 /** Constant with value POSITIVE_INFINITY. */
34 public static final Frequency POSITIVE_INFINITY = Frequency.ofSi(Double.POSITIVE_INFINITY);
35
36 /** Constant with value NEGATIVE_INFINITY. */
37 public static final Frequency NEGATIVE_INFINITY = Frequency.ofSi(Double.NEGATIVE_INFINITY);
38
39 /** Constant with value MAX_VALUE. */
40 public static final Frequency POS_MAXVALUE = Frequency.ofSi(Double.MAX_VALUE);
41
42 /** Constant with value -MAX_VALUE. */
43 public static final Frequency NEG_MAXVALUE = Frequency.ofSi(-Double.MAX_VALUE);
44
45 /** */
46 private static final long serialVersionUID = 600L;
47
48 /**
49 * Instantiate a Frequency quantity with a unit.
50 * @param valueInUnit the value, expressed in the unit
51 * @param unit the unit in which the value is expressed
52 */
53 public Frequency(final double valueInUnit, final Frequency.Unit unit)
54 {
55 super(valueInUnit, unit);
56 }
57
58 /**
59 * Instantiate a Frequency quantity with a unit, expressed as a String.
60 * @param valueInUnit the value, expressed in the unit
61 * @param abbreviation the String abbreviation of the unit in which the value is expressed
62 */
63 public Frequency(final double valueInUnit, final String abbreviation)
64 {
65 this(valueInUnit, Units.resolve(Frequency.Unit.class, abbreviation));
66 }
67
68 /**
69 * Construct Frequency quantity.
70 * @param value Scalar from which to construct this instance
71 */
72 public Frequency(final Frequency value)
73 {
74 super(value.si(), Frequency.Unit.SI);
75 setDisplayUnit(value.getDisplayUnit());
76 }
77
78 /**
79 * Return a Frequency instance based on an SI value.
80 * @param si the si value
81 * @return the Frequency instance based on an SI value
82 */
83 public static Frequency ofSi(final double si)
84 {
85 return new Frequency(si, Frequency.Unit.SI);
86 }
87
88 @Override
89 public Frequency instantiateSi(final double si)
90 {
91 return ofSi(si);
92 }
93
94 @Override
95 public SIUnit siUnit()
96 {
97 return Frequency.Unit.SI_UNIT;
98 }
99
100 /**
101 * Returns a Frequency representation of a textual representation of a value with a unit. The String representation that can
102 * be parsed is the double value in the unit, followed by a localized or English abbreviation of the unit. Spaces are
103 * allowed, but not required, between the value and the unit.
104 * @param text the textual representation to parse into a Frequency
105 * @return the Scalar representation of the value in its unit
106 * @throws IllegalArgumentException when the text cannot be parsed
107 * @throws NullPointerException when the text argument is null
108 */
109 public static Frequency valueOf(final String text)
110 {
111 return Quantity.valueOf(text, ZERO);
112 }
113
114 /**
115 * Returns a Frequency based on a value and the textual representation of the unit, which can be localized.
116 * @param valueInUnit the value, expressed in the unit as given by unitString
117 * @param unitString the textual representation of the unit
118 * @return the Scalar representation of the value in its unit
119 * @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
120 * @throws NullPointerException when the unitString argument is null
121 */
122 public static Frequency of(final double valueInUnit, final String unitString)
123 {
124 return Quantity.of(valueInUnit, unitString, ZERO);
125 }
126
127 @Override
128 public Frequency.Unit getDisplayUnit()
129 {
130 return (Frequency.Unit) super.getDisplayUnit();
131 }
132
133 /**
134 * Calculate the division of Frequency and Frequency, which results in a Dimensionless quantity.
135 * @param v quantity
136 * @return quantity as a division of Frequency and Frequency
137 */
138 public final Dimensionless divide(final Frequency v)
139 {
140 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
141 }
142
143 /**
144 * Calculate the multiplication of Frequency and Duration, which results in a Dimensionless scalar.
145 * @param v scalar
146 * @return scalar as a multiplication of Frequency and Duration
147 */
148 public final Dimensionless multiply(final Duration v)
149 {
150 return new Dimensionless(this.si() * v.si(), Unitless.BASE);
151 }
152
153 /**
154 * Calculate the multiplication of Frequency and Length, which results in a Speed scalar.
155 * @param v scalar
156 * @return scalar as a multiplication of Frequency and Length
157 */
158 public final Speed multiply(final Length v)
159 {
160 return new Speed(this.si() * v.si(), Speed.Unit.SI);
161 }
162
163 /**
164 * Calculate the multiplication of Frequency and Speed, which results in a Acceleration scalar.
165 * @param v scalar
166 * @return scalar as a multiplication of Frequency and Speed
167 */
168 public final Acceleration multiply(final Speed v)
169 {
170 return new Acceleration(this.si() * v.si(), Acceleration.Unit.SI);
171 }
172
173 /**
174 * Calculate the multiplication of Frequency and Energy, which results in a Power scalar.
175 * @param v scalar
176 * @return scalar as a multiplication of Frequency and Energy
177 */
178 public final Power multiply(final Energy v)
179 {
180 return new Power(this.si() * v.si(), Power.Unit.SI);
181 }
182
183 /**
184 * Calculate the multiplication of Frequency and Angle, which results in a AngularVelocity scalar.
185 * @param v scalar
186 * @return scalar as a multiplication of Frequency and Angle
187 */
188 public final AngularVelocity multiply(final Angle v)
189 {
190 return new AngularVelocity(this.si() * v.si(), AngularVelocity.Unit.SI);
191 }
192
193 /**
194 * Calculate the multiplication of Frequency and AngularVelocity, which results in a AngularAcceleration scalar.
195 * @param v scalar
196 * @return scalar as a multiplication of Frequency and AngularVelocity
197 */
198 public final AngularAcceleration multiply(final AngularVelocity v)
199 {
200 return new AngularAcceleration(this.si() * v.si(), AngularAcceleration.Unit.SI);
201 }
202
203 @Override
204 public Duration reciprocal()
205 {
206 return Duration.ofSi(1.0 / this.si());
207 }
208
209 /******************************************************************************************************/
210 /********************************************** UNIT CLASS ********************************************/
211 /******************************************************************************************************/
212
213 /**
214 * Frequency.Unit encodes the units of frequency.
215 * <p>
216 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
217 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
218 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
219 * @author Alexander Verbraeck
220 */
221 @SuppressWarnings("checkstyle:constantname")
222 public static class Unit extends AbstractUnit<Frequency.Unit, Frequency>
223 {
224 /** The dimensions of frequency: /s. */
225 public static final SIUnit SI_UNIT = SIUnit.of("/s");
226
227 /** hertz. */
228 public static final Frequency.Unit Hz = new Frequency.Unit("Hz", "hertz", 1.0, UnitSystem.SI_DERIVED);
229
230 /** The SI or BASE unit. */
231 public static final Frequency.Unit SI = Hz.generateSiPrefixes(false, false);
232
233 /** kiloHertz. */
234 public static final Frequency.Unit kHz = Units.resolve(Frequency.Unit.class, "kHz");
235
236 /** megaHertz. */
237 public static final Frequency.Unit MHz = Units.resolve(Frequency.Unit.class, "MHz");
238
239 /** gigaHertz. */
240 public static final Frequency.Unit GHz = Units.resolve(Frequency.Unit.class, "GHz");
241
242 /** teraHertz. */
243 public static final Frequency.Unit THz = Units.resolve(Frequency.Unit.class, "THz");
244
245 /** Revolutions per minute = 1/60 Hz. */
246 public static final Frequency.Unit rpm = Hz.deriveUnit("rpm", "revolutions per minute", 1.0 / 60.0, UnitSystem.OTHER);
247
248 /**
249 * Create a new Frequency unit.
250 * @param id the id or main abbreviation of the unit
251 * @param name the full name of the unit
252 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
253 * @param unitSystem the unit system such as SI or IMPERIAL
254 */
255 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
256 {
257 super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
258 }
259
260 /**
261 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
262 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
263 * @param displayAbbreviation the display abbreviation of the unit
264 * @param name the full name of the unit
265 * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
266 * @param unitSystem unit system, e.g. SI or Imperial
267 */
268 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
269 final UnitSystem unitSystem)
270 {
271 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
272 }
273
274 @Override
275 public SIUnit siUnit()
276 {
277 return SI_UNIT;
278 }
279
280 @Override
281 public Unit getBaseUnit()
282 {
283 return SI;
284 }
285
286 @Override
287 public Frequency ofSi(final double si)
288 {
289 return Frequency.ofSi(si);
290 }
291
292 @Override
293 public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
294 final double scaleFactor, final UnitSystem unitSystem)
295 {
296 if (getScale() instanceof LinearScale ls)
297 {
298 return new Frequency.Unit(textualAbbreviation, displayAbbreviation, name,
299 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
300 }
301 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
302 }
303
304 }
305 }