1 package org.djunits.quantity;
2
3 import org.djunits.quantity.def.Quantity;
4 import org.djunits.unit.AbstractUnit;
5 import org.djunits.unit.UnitInterface;
6 import org.djunits.unit.UnitRuntimeException;
7 import org.djunits.unit.Unitless;
8 import org.djunits.unit.Units;
9 import org.djunits.unit.scale.IdentityScale;
10 import org.djunits.unit.scale.LinearScale;
11 import org.djunits.unit.scale.Scale;
12 import org.djunits.unit.si.SIPrefix;
13 import org.djunits.unit.si.SIPrefixes;
14 import org.djunits.unit.si.SIUnit;
15 import org.djunits.unit.system.UnitSystem;
16
17 /**
18 * Frequency encodes the number of events per unit of duration.
19 * <p>
20 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
21 * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
22 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
23 * @author Alexander Verbraeck
24 */
25 public class Frequency extends Quantity<Frequency>
26 {
27 /** Constant with value zero. */
28 public static final Frequency ZERO = ofSi(0.0);
29
30 /** Constant with value one. */
31 public static final Frequency ONE = ofSi(1.0);
32
33 /** Constant with value NaN. */
34 @SuppressWarnings("checkstyle:constantname")
35 public static final Frequency NaN = ofSi(Double.NaN);
36
37 /** Constant with value POSITIVE_INFINITY. */
38 public static final Frequency POSITIVE_INFINITY = ofSi(Double.POSITIVE_INFINITY);
39
40 /** Constant with value NEGATIVE_INFINITY. */
41 public static final Frequency NEGATIVE_INFINITY = ofSi(Double.NEGATIVE_INFINITY);
42
43 /** Constant with value MAX_VALUE. */
44 public static final Frequency POS_MAXVALUE = ofSi(Double.MAX_VALUE);
45
46 /** Constant with value -MAX_VALUE. */
47 public static final Frequency NEG_MAXVALUE = ofSi(-Double.MAX_VALUE);
48
49 /** */
50 private static final long serialVersionUID = 600L;
51
52 /**
53 * Instantiate a Frequency quantity with an SI or base value and a display unit.
54 * @param value the quantity value expressed in the SI or base unit
55 * @param displayUnit the display unit to use
56 * @param useSi use SI value when true, use value in unit when false
57 */
58 public Frequency(final double value, final Frequency.Unit displayUnit, final boolean useSi)
59 {
60 super(value, displayUnit, useSi);
61 }
62
63 /**
64 * Instantiate a Frequency quantity expressed in the given unit.
65 * @param valueInUnit the quantity value expressed in the given unit
66 * @param unit the unit of the value, also acts as the display unit
67 */
68 public Frequency(final double valueInUnit, final Frequency.Unit unit)
69 {
70 this(valueInUnit, unit, false);
71 }
72
73 /**
74 * Return a Frequency instance based on an SI value.
75 * @param si the si value
76 * @return the Frequency instance based on an SI value
77 */
78 public static Frequency ofSi(final double si)
79 {
80 return new Frequency(si, Frequency.Unit.SI, true);
81 }
82
83 /**
84 * Instantiate a Frequency quantity with an SI or base value and a display unit.
85 * @param siValue the quantity value expressed in the SI or base unit
86 * @param displayUnit the display unit to use
87 * @return the Frequency instance based on an SI value with the given display unit
88 */
89 public static Frequency ofSi(final double siValue, final Frequency.Unit displayUnit)
90 {
91 return new Frequency(siValue, displayUnit, true);
92 }
93
94 @Override
95 public Frequency instantiateSi(final double siValue, final UnitInterface<Frequency> displayUnit)
96 {
97 return new Frequency(siValue, (Frequency.Unit) displayUnit, true);
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 expressed in the unit.
116 * @param valueInUnit the value, expressed in the given unit
117 * @param unit the unit of the value, also acts as the display unit
118 * @return ab Frequency representation of the value in its unit
119 */
120 public static Frequency of(final double valueInUnit, final Frequency.Unit unit)
121 {
122 return new Frequency(valueInUnit, unit);
123 }
124
125 /**
126 * Returns a Frequency based on a value and the textual representation of the unit, which can be localized.
127 * @param valueInUnit the value, expressed in the unit as given by unitString
128 * @param unitString the textual representation of the unit
129 * @return the Scalar representation of the value in its unit
130 * @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
131 * @throws NullPointerException when the unitString argument is null
132 */
133 public static Frequency of(final double valueInUnit, final String unitString)
134 {
135 return Quantity.of(valueInUnit, unitString, ZERO);
136 }
137
138 @Override
139 public Frequency.Unit getDisplayUnit()
140 {
141 return (Frequency.Unit) super.getDisplayUnit();
142 }
143
144 /**
145 * Calculate the division of Frequency and Frequency, which results in a Dimensionless quantity.
146 * @param v quantity
147 * @return quantity as a division of Frequency and Frequency
148 */
149 public Dimensionless divide(final Frequency v)
150 {
151 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
152 }
153
154 /**
155 * Calculate the multiplication of Frequency and Duration, which results in a Dimensionless scalar.
156 * @param v scalar
157 * @return scalar as a multiplication of Frequency and Duration
158 */
159 public Dimensionless multiply(final Duration v)
160 {
161 return new Dimensionless(this.si() * v.si(), Unitless.BASE);
162 }
163
164 /**
165 * Calculate the multiplication of Frequency and Length, which results in a Speed scalar.
166 * @param v scalar
167 * @return scalar as a multiplication of Frequency and Length
168 */
169 public Speed multiply(final Length v)
170 {
171 return new Speed(this.si() * v.si(), Speed.Unit.SI);
172 }
173
174 /**
175 * Calculate the multiplication of Frequency and Speed, which results in a Acceleration scalar.
176 * @param v scalar
177 * @return scalar as a multiplication of Frequency and Speed
178 */
179 public Acceleration multiply(final Speed v)
180 {
181 return new Acceleration(this.si() * v.si(), Acceleration.Unit.SI);
182 }
183
184 /**
185 * Calculate the multiplication of Frequency and Energy, which results in a Power scalar.
186 * @param v scalar
187 * @return scalar as a multiplication of Frequency and Energy
188 */
189 public Power multiply(final Energy v)
190 {
191 return new Power(this.si() * v.si(), Power.Unit.SI);
192 }
193
194 /**
195 * Calculate the multiplication of Frequency and Angle, which results in a AngularVelocity scalar.
196 * @param v scalar
197 * @return scalar as a multiplication of Frequency and Angle
198 */
199 public AngularVelocity multiply(final Angle v)
200 {
201 return new AngularVelocity(this.si() * v.si(), AngularVelocity.Unit.SI);
202 }
203
204 /**
205 * Calculate the multiplication of Frequency and AngularVelocity, which results in a AngularAcceleration scalar.
206 * @param v scalar
207 * @return scalar as a multiplication of Frequency and AngularVelocity
208 */
209 public AngularAcceleration multiply(final AngularVelocity v)
210 {
211 return new AngularAcceleration(this.si() * v.si(), AngularAcceleration.Unit.SI);
212 }
213
214 @Override
215 public Duration reciprocal()
216 {
217 return Duration.ofSi(1.0 / this.si());
218 }
219
220 /******************************************************************************************************/
221 /********************************************** UNIT CLASS ********************************************/
222 /******************************************************************************************************/
223
224 /**
225 * Frequency.Unit encodes the units of frequency.
226 * <p>
227 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
228 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
229 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
230 * @author Alexander Verbraeck
231 */
232 @SuppressWarnings("checkstyle:constantname")
233 public static class Unit extends AbstractUnit<Frequency>
234 {
235 /** The dimensions of frequency: /s. */
236 public static final SIUnit SI_UNIT = SIUnit.of("/s");
237
238 /** hertz. */
239 public static final Frequency.Unit Hz =
240 new Frequency.Unit("Hz", "Hz", "hertz", IdentityScale.SCALE, UnitSystem.SI_DERIVED, SIPrefixes.getSiPrefix(""));
241
242 /** The SI or BASE unit. */
243 public static final Frequency.Unit SI = (Unit) Hz.generateSiPrefixes(false, false);
244
245 /** kiloHertz. */
246 public static final Frequency.Unit kHz = Units.resolve(Frequency.Unit.class, "kHz");
247
248 /** megaHertz. */
249 public static final Frequency.Unit MHz = Units.resolve(Frequency.Unit.class, "MHz");
250
251 /** gigaHertz. */
252 public static final Frequency.Unit GHz = Units.resolve(Frequency.Unit.class, "GHz");
253
254 /** teraHertz. */
255 public static final Frequency.Unit THz = Units.resolve(Frequency.Unit.class, "THz");
256
257 /** Revolutions per minute = 1/60 Hz. */
258 public static final Frequency.Unit rpm =
259 Hz.deriveUnit("rpm", "rpm", "revolutions per minute", 1.0 / 60.0, UnitSystem.OTHER, null);
260
261 /**
262 * Create a new Frequency unit.
263 * @param id the id or main abbreviation of the unit
264 * @param name the full name of the unit
265 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
266 * @param unitSystem the unit system such as SI or IMPERIAL
267 */
268 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
269 {
270 super(id, name, scaleFactorToBaseUnit, unitSystem);
271 }
272
273 /**
274 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
275 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
276 * @param displayAbbreviation the display abbreviation of the unit
277 * @param name the full name of the unit
278 * @param scale the scale to use to convert from this unit to the standard (e.g., SI, BASE) unit
279 * @param unitSystem unit system, e.g. SI or Imperial
280 * @param siPrefix the SI Prefix of this unit
281 */
282 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
283 final UnitSystem unitSystem, final SIPrefix siPrefix)
284 {
285 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem, siPrefix);
286 }
287
288 @Override
289 public SIUnit siUnit()
290 {
291 return SI_UNIT;
292 }
293
294 @Override
295 public Unit getBaseUnit()
296 {
297 return SI;
298 }
299
300 @Override
301 public Frequency ofSi(final double si, final UnitInterface<Frequency> displayUnit)
302 {
303 return new Frequency(si, (Unit) displayUnit, true);
304 }
305
306 @Override
307 public Frequency.Unit deriveUnit(final String abbreviation, final String name, final double scaleFactor,
308 final UnitSystem unitSystem)
309 {
310 return (Unit) super.deriveUnit(abbreviation, name, scaleFactor, unitSystem);
311 }
312
313 @Override
314 public Frequency.Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
315 final double scaleFactor, final UnitSystem unitSystem, final SIPrefix siPrefix)
316 {
317 if (getScale() instanceof LinearScale ls)
318 {
319 return new Frequency.Unit(textualAbbreviation, displayAbbreviation, name,
320 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem, siPrefix);
321 }
322 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
323 }
324
325 }
326
327 }