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.IdentityScale;
9 import org.djunits.unit.scale.LinearScale;
10 import org.djunits.unit.scale.Scale;
11 import org.djunits.unit.si.SIUnit;
12 import org.djunits.unit.system.UnitSystem;
13
14 /**
15 * Speed is the rate of change of position over time.
16 * <p>
17 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
18 * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
19 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
20 * @author Alexander Verbraeck
21 */
22 public class Speed extends Quantity<Speed>
23 {
24 /** Constant with value zero. */
25 public static final Speed ZERO = Speed.ofSi(0.0);
26
27 /** Constant with value one. */
28 public static final Speed ONE = Speed.ofSi(1.0);
29
30 /** Constant with value NaN. */
31 @SuppressWarnings("checkstyle:constantname")
32 public static final Speed NaN = Speed.ofSi(Double.NaN);
33
34 /** Constant with value POSITIVE_INFINITY. */
35 public static final Speed POSITIVE_INFINITY = Speed.ofSi(Double.POSITIVE_INFINITY);
36
37 /** Constant with value NEGATIVE_INFINITY. */
38 public static final Speed NEGATIVE_INFINITY = Speed.ofSi(Double.NEGATIVE_INFINITY);
39
40 /** Constant with value MAX_VALUE. */
41 public static final Speed POS_MAXVALUE = Speed.ofSi(Double.MAX_VALUE);
42
43 /** Constant with value -MAX_VALUE. */
44 public static final Speed NEG_MAXVALUE = Speed.ofSi(-Double.MAX_VALUE);
45
46 /** */
47 private static final long serialVersionUID = 600L;
48
49 /**
50 * Instantiate a Speed quantity with a unit.
51 * @param valueInUnit the value, expressed in the unit
52 * @param unit the unit in which the value is expressed
53 */
54 public Speed(final double valueInUnit, final Speed.Unit unit)
55 {
56 super(valueInUnit, unit);
57 }
58
59 /**
60 * Instantiate a Speed quantity with a unit, expressed as a String.
61 * @param valueInUnit the value, expressed in the unit
62 * @param abbreviation the String abbreviation of the unit in which the value is expressed
63 */
64 public Speed(final double valueInUnit, final String abbreviation)
65 {
66 this(valueInUnit, Units.resolve(Speed.Unit.class, abbreviation));
67 }
68
69 /**
70 * Construct Speed quantity.
71 * @param value Scalar from which to construct this instance
72 */
73 public Speed(final Speed value)
74 {
75 super(value.si(), Speed.Unit.SI);
76 setDisplayUnit(value.getDisplayUnit());
77 }
78
79 /**
80 * Return a Speed instance based on an SI value.
81 * @param si the si value
82 * @return the Speed instance based on an SI value
83 */
84 public static Speed ofSi(final double si)
85 {
86 return new Speed(si, Speed.Unit.SI);
87 }
88
89 @Override
90 public Speed instantiateSi(final double si)
91 {
92 return ofSi(si);
93 }
94
95 @Override
96 public SIUnit siUnit()
97 {
98 return Speed.Unit.SI_UNIT;
99 }
100
101 /**
102 * Returns a Speed representation of a textual representation of a value with a unit. The String representation that can be
103 * parsed is the double value in the unit, followed by a localized or English abbreviation of the unit. Spaces are allowed,
104 * but not required, between the value and the unit.
105 * @param text the textual representation to parse into a Speed
106 * @return the Scalar representation of the value in its unit
107 * @throws IllegalArgumentException when the text cannot be parsed
108 * @throws NullPointerException when the text argument is null
109 */
110 public static Speed valueOf(final String text)
111 {
112 return Quantity.valueOf(text, ZERO);
113 }
114
115 /**
116 * Returns a Speed based on a value and the textual representation of the unit, which can be localized.
117 * @param valueInUnit the value, expressed in the unit as given by unitString
118 * @param unitString the textual representation of the unit
119 * @return the Scalar representation of the value in its unit
120 * @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
121 * @throws NullPointerException when the unitString argument is null
122 */
123 public static Speed of(final double valueInUnit, final String unitString)
124 {
125 return Quantity.of(valueInUnit, unitString, ZERO);
126 }
127
128 @Override
129 public Speed.Unit getDisplayUnit()
130 {
131 return (Speed.Unit) super.getDisplayUnit();
132 }
133
134 /**
135 * Calculate the division of Speed and Speed, which results in a Dimensionless scalar.
136 * @param v scalar
137 * @return scalar as a division of Speed and Speed
138 */
139 public final Dimensionless divide(final Speed v)
140 {
141 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
142 }
143
144 /**
145 * Calculate the multiplication of Speed and Area, which results in a FlowVolume scalar.
146 * @param v scalar
147 * @return scalar as a multiplication of Speed and Area
148 */
149 public final FlowVolume multiply(final Area v)
150 {
151 return new FlowVolume(this.si() * v.si(), FlowVolume.Unit.SI);
152 }
153
154 /**
155 * Calculate the multiplication of Speed and Force, which results in a Power scalar.
156 * @param v scalar
157 * @return scalar as a multiplication of Speed and Force
158 */
159 public final Power multiply(final Force v)
160 {
161 return new Power(this.si() * v.si(), Power.Unit.SI);
162 }
163
164 /**
165 * Calculate the multiplication of Speed and Frequency, which results in a Acceleration scalar.
166 * @param v scalar
167 * @return scalar as a multiplication of Speed and Frequency
168 */
169 public final Acceleration multiply(final Frequency v)
170 {
171 return new Acceleration(this.si() * v.si(), Acceleration.Unit.SI);
172 }
173
174 /**
175 * Calculate the division of Speed and Length, which results in a Frequency scalar.
176 * @param v scalar
177 * @return scalar as a division of Speed and Length
178 */
179 public final Frequency divide(final Length v)
180 {
181 return new Frequency(this.si() / v.si(), Frequency.Unit.SI);
182 }
183
184 /**
185 * Calculate the division of Speed and Frequency, which results in a Length scalar.
186 * @param v scalar
187 * @return scalar as a division of Speed and Frequency
188 */
189 public final Length divide(final Frequency v)
190 {
191 return new Length(this.si() / v.si(), Length.Unit.SI);
192 }
193
194 /**
195 * Calculate the multiplication of Speed and LinearObjectDensity, which results in a Frequency scalar.
196 * @param v scalar
197 * @return scalar as a multiplication of Speed and LinearObjectDensity
198 */
199 public final Frequency multiply(final LinearObjectDensity v)
200 {
201 return new Frequency(this.si() * v.si(), Frequency.Unit.SI);
202 }
203
204 /**
205 * Calculate the multiplication of Speed and Duration, which results in a Length scalar.
206 * @param v scalar
207 * @return scalar as a multiplication of Speed and Duration
208 */
209 public final Length multiply(final Duration v)
210 {
211 return new Length(this.si() * v.si(), Length.Unit.SI);
212 }
213
214 /**
215 * Calculate the division of Speed and Duration, which results in a Acceleration scalar.
216 * @param v scalar
217 * @return scalar as a division of Speed and Duration
218 */
219 public final Acceleration divide(final Duration v)
220 {
221 return new Acceleration(this.si() / v.si(), Acceleration.Unit.SI);
222 }
223
224 /**
225 * Calculate the division of Speed and Acceleration, which results in a Duration scalar.
226 * @param v scalar
227 * @return scalar as a division of Speed and Acceleration
228 */
229 public final Duration divide(final Acceleration v)
230 {
231 return new Duration(this.si() / v.si(), Duration.Unit.SI);
232 }
233
234 /**
235 * Calculate the multiplication of Speed and FlowMass, which results in a Force scalar.
236 * @param v scalar
237 * @return scalar as a multiplication of Speed and FlowMass
238 */
239 public final Force multiply(final FlowMass v)
240 {
241 return new Force(this.si() * v.si(), Force.Unit.SI);
242 }
243
244 /**
245 * Calculate the multiplication of Speed and Mass, which results in a Momentum scalar.
246 * @param v scalar
247 * @return scalar as a multiplication of Speed and Mass
248 */
249 public final Momentum multiply(final Mass v)
250 {
251 return new Momentum(this.si() * v.si(), Momentum.Unit.SI);
252 }
253
254 /**
255 * Calculate the multiplication of Speed and Momentum, which results in a Energy scalar.
256 * @param v scalar
257 * @return scalar as a multiplication of Speed and Momentum
258 */
259 public final Energy multiply(final Momentum v)
260 {
261 return new Energy(this.si() * v.si(), Energy.Unit.SI);
262 }
263
264 /******************************************************************************************************/
265 /********************************************** UNIT CLASS ********************************************/
266 /******************************************************************************************************/
267
268 /**
269 * Speed.Unit encodes the units of the rate of change of a position over time.
270 * <p>
271 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
272 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
273 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
274 * @author Alexander Verbraeck
275 */
276 @SuppressWarnings("checkstyle:constantname")
277 public static class Unit extends AbstractUnit<Speed.Unit, Speed>
278 {
279 /** The dimensions of Speed: m/s. */
280 public static final SIUnit SI_UNIT = SIUnit.of("m/s");
281
282 /** Meter per second. */
283 public static final Speed.Unit m_s =
284 new Speed.Unit("m/s", "m/s", "meter per second", IdentityScale.SCALE, UnitSystem.SI_DERIVED);
285
286 /** The SI or BASE unit. */
287 public static final Speed.Unit SI = m_s;
288
289 /** m/h. */
290 public static final Speed.Unit m_h =
291 new Speed.Unit("m/h", "m/h", "meter per hour", new LinearScale(1.0, 3600.0), UnitSystem.SI_ACCEPTED);
292
293 /** km/s. */
294 public static final Speed.Unit km_s =
295 new Speed.Unit("km/s", "km/s", "kilometer per second", new LinearScale(1000.0), UnitSystem.SI_ACCEPTED);
296
297 /** km/h. */
298 public static final Speed.Unit km_h =
299 new Speed.Unit("km/h", "km/h", "kilometer per hour", new LinearScale(1000.0, 3600.0), UnitSystem.SI_ACCEPTED);
300
301 /** in/s. */
302 public static final Speed.Unit in_s =
303 new Speed.Unit("in/s", "in/s", "inch per second", new LinearScale(Length.Unit.CONST_IN), UnitSystem.IMPERIAL);
304
305 /** in/min. */
306 public static final Speed.Unit in_min = new Speed.Unit("in/min", "in/min", "inch per minute",
307 new LinearScale(Length.Unit.CONST_IN, 60.0), UnitSystem.IMPERIAL);
308
309 /** in/h. */
310 public static final Speed.Unit in_h = new Speed.Unit("in/h", "in/h", "inch per hour",
311 new LinearScale(Length.Unit.CONST_IN, 3600.0), UnitSystem.IMPERIAL);
312
313 /** ft/s. */
314 public static final Speed.Unit ft_s =
315 new Speed.Unit("ft/s", "ft/s", "foot per second", new LinearScale(Length.Unit.CONST_FT), UnitSystem.IMPERIAL);
316
317 /** ft/min. */
318 public static final Speed.Unit ft_min = new Speed.Unit("ft/min", "ft/min", "foot per minute",
319 new LinearScale(Length.Unit.CONST_FT, 60.0), UnitSystem.IMPERIAL);
320
321 /** ft/h. */
322 public static final Speed.Unit ft_h = new Speed.Unit("ft/h", "ft/h", "foot per hour",
323 new LinearScale(Length.Unit.CONST_FT, 3600.0), UnitSystem.IMPERIAL);
324
325 /** mi/s. */
326 public static final Speed.Unit mi_s =
327 new Speed.Unit("mi/s", "mi/s", "mile per second", new LinearScale(Length.Unit.CONST_MI), UnitSystem.IMPERIAL);
328
329 /** mi/min. */
330 public static final Speed.Unit mi_min = new Speed.Unit("mi/min", "mi/min", "mile per minute",
331 new LinearScale(Length.Unit.CONST_MI, 60.0), UnitSystem.IMPERIAL);
332
333 /** mi/h. */
334 public static final Speed.Unit mi_h = new Speed.Unit("mi/h", "mi/h", "mile per hour",
335 new LinearScale(Length.Unit.CONST_MI, 3600.0), UnitSystem.IMPERIAL);
336
337 /** knot = Nautical Mile per hour. */
338 public static final Speed.Unit kt = new Speed.Unit("kt", "knot", Length.Unit.CONST_NM / 3600.0, UnitSystem.OTHER);
339
340 /**
341 * Create a new Speed unit.
342 * @param id the id or main abbreviation of the unit
343 * @param name the full name of the unit
344 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
345 * @param unitSystem the unit system such as SI or IMPERIAL
346 */
347 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
348 {
349 super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
350 }
351
352 /**
353 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
354 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
355 * @param displayAbbreviation the display abbreviation of the unit
356 * @param name the full name of the unit
357 * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
358 * @param unitSystem unit system, e.g. SI or Imperial
359 */
360 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
361 final UnitSystem unitSystem)
362 {
363 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
364 }
365
366 @Override
367 public SIUnit siUnit()
368 {
369 return SI_UNIT;
370 }
371
372 @Override
373 public Unit getBaseUnit()
374 {
375 return SI;
376 }
377
378 @Override
379 public Speed ofSi(final double si)
380 {
381 return Speed.ofSi(si);
382 }
383
384 @Override
385 public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
386 final double scaleFactor, final UnitSystem unitSystem)
387 {
388 if (getScale() instanceof LinearScale ls)
389 {
390 return new Speed.Unit(textualAbbreviation, displayAbbreviation, name,
391 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
392 }
393 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
394 }
395
396 }
397 }