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