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.scale.IdentityScale;
9 import org.djunits.unit.scale.LinearScale;
10 import org.djunits.unit.scale.Scale;
11 import org.djunits.unit.si.SIPrefix;
12 import org.djunits.unit.si.SIUnit;
13 import org.djunits.unit.system.UnitSystem;
14
15 /**
16 * Speed is the rate of change of position over time.
17 * <p>
18 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
19 * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
20 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
21 * @author Alexander Verbraeck
22 */
23 public class Speed extends Quantity<Speed>
24 {
25 /** Constant with value zero. */
26 public static final Speed ZERO = ofSi(0.0);
27
28 /** Constant with value one. */
29 public static final Speed ONE = ofSi(1.0);
30
31 /** Constant with value NaN. */
32 @SuppressWarnings("checkstyle:constantname")
33 public static final Speed NaN = ofSi(Double.NaN);
34
35 /** Constant with value POSITIVE_INFINITY. */
36 public static final Speed POSITIVE_INFINITY = ofSi(Double.POSITIVE_INFINITY);
37
38 /** Constant with value NEGATIVE_INFINITY. */
39 public static final Speed NEGATIVE_INFINITY = ofSi(Double.NEGATIVE_INFINITY);
40
41 /** Constant with value MAX_VALUE. */
42 public static final Speed POS_MAXVALUE = ofSi(Double.MAX_VALUE);
43
44 /** Constant with value -MAX_VALUE. */
45 public static final Speed NEG_MAXVALUE = ofSi(-Double.MAX_VALUE);
46
47 /** */
48 private static final long serialVersionUID = 600L;
49
50 /**
51 * Instantiate a Speed quantity with an SI or base value and a display unit.
52 * @param value the quantity value expressed in the SI or base unit
53 * @param displayUnit the display unit to use
54 * @param useSi use SI value when true, use value in unit when false
55 */
56 public Speed(final double value, final Speed.Unit displayUnit, final boolean useSi)
57 {
58 super(value, displayUnit, useSi);
59 }
60
61 /**
62 * Instantiate a Speed quantity expressed in the given unit.
63 * @param valueInUnit the quantity value expressed in the given unit
64 * @param unit the unit of the value, also acts as the display unit
65 */
66 public Speed(final double valueInUnit, final Speed.Unit unit)
67 {
68 this(valueInUnit, unit, false);
69 }
70
71 /**
72 * Return a Speed instance based on an SI value.
73 * @param si the si value
74 * @return the Speed instance based on an SI value
75 */
76 public static Speed ofSi(final double si)
77 {
78 return new Speed(si, Speed.Unit.SI, true);
79 }
80
81 /**
82 * Instantiate a Speed quantity with an SI or base value and a display unit.
83 * @param siValue the quantity value expressed in the SI or base unit
84 * @param displayUnit the display unit to use
85 * @return the Speed instance based on an SI value with the given display unit
86 */
87 public static Speed ofSi(final double siValue, final Speed.Unit displayUnit)
88 {
89 return new Speed(siValue, displayUnit, true);
90 }
91
92 @Override
93 public Speed instantiateSi(final double siValue, final UnitInterface<Speed> displayUnit)
94 {
95 return new Speed(siValue, (Speed.Unit) displayUnit, true);
96 }
97
98 /**
99 * Returns a Speed representation of a textual representation of a value with a unit. The String representation that can be
100 * parsed is the double value in the unit, followed by a localized or English abbreviation of the unit. Spaces are allowed,
101 * but not required, between the value and the unit.
102 * @param text the textual representation to parse into a Speed
103 * @return the Scalar representation of the value in its unit
104 * @throws IllegalArgumentException when the text cannot be parsed
105 * @throws NullPointerException when the text argument is null
106 */
107 public static Speed valueOf(final String text)
108 {
109 return Quantity.valueOf(text, ZERO);
110 }
111
112 /**
113 * Returns a Speed based on a value expressed in the unit.
114 * @param valueInUnit the value, expressed in the given unit
115 * @param unit the unit of the value, also acts as the display unit
116 * @return ab Speed representation of the value in its unit
117 */
118 public static Speed of(final double valueInUnit, final Speed.Unit unit)
119 {
120 return new Speed(valueInUnit, unit);
121 }
122
123 /**
124 * Returns a Speed based on a value and the textual representation of the unit, which can be localized.
125 * @param valueInUnit the value, expressed in the unit as given by unitString
126 * @param unitString the textual representation of the unit
127 * @return the Scalar representation of the value in its unit
128 * @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
129 * @throws NullPointerException when the unitString argument is null
130 */
131 public static Speed of(final double valueInUnit, final String unitString)
132 {
133 return Quantity.of(valueInUnit, unitString, ZERO);
134 }
135
136 @Override
137 public Speed.Unit getDisplayUnit()
138 {
139 return (Speed.Unit) super.getDisplayUnit();
140 }
141
142 /**
143 * Calculate the division of Speed and Speed, which results in a Dimensionless scalar.
144 * @param v scalar
145 * @return scalar as a division of Speed and Speed
146 */
147 public Dimensionless divide(final Speed v)
148 {
149 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
150 }
151
152 /**
153 * Calculate the multiplication of Speed and Area, which results in a FlowVolume scalar.
154 * @param v scalar
155 * @return scalar as a multiplication of Speed and Area
156 */
157 public FlowVolume multiply(final Area v)
158 {
159 return new FlowVolume(this.si() * v.si(), FlowVolume.Unit.SI);
160 }
161
162 /**
163 * Calculate the multiplication of Speed and Force, which results in a Power scalar.
164 * @param v scalar
165 * @return scalar as a multiplication of Speed and Force
166 */
167 public Power multiply(final Force v)
168 {
169 return new Power(this.si() * v.si(), Power.Unit.SI);
170 }
171
172 /**
173 * Calculate the multiplication of Speed and Frequency, which results in a Acceleration scalar.
174 * @param v scalar
175 * @return scalar as a multiplication of Speed and Frequency
176 */
177 public Acceleration multiply(final Frequency v)
178 {
179 return new Acceleration(this.si() * v.si(), Acceleration.Unit.SI);
180 }
181
182 /**
183 * Calculate the division of Speed and Length, which results in a Frequency scalar.
184 * @param v scalar
185 * @return scalar as a division of Speed and Length
186 */
187 public Frequency divide(final Length v)
188 {
189 return new Frequency(this.si() / v.si(), Frequency.Unit.SI);
190 }
191
192 /**
193 * Calculate the division of Speed and Frequency, which results in a Length scalar.
194 * @param v scalar
195 * @return scalar as a division of Speed and Frequency
196 */
197 public Length divide(final Frequency v)
198 {
199 return new Length(this.si() / v.si(), Length.Unit.SI);
200 }
201
202 /**
203 * Calculate the multiplication of Speed and LinearObjectDensity, which results in a Frequency scalar.
204 * @param v scalar
205 * @return scalar as a multiplication of Speed and LinearObjectDensity
206 */
207 public Frequency multiply(final LinearObjectDensity v)
208 {
209 return new Frequency(this.si() * v.si(), Frequency.Unit.SI);
210 }
211
212 /**
213 * Calculate the multiplication of Speed and Duration, which results in a Length scalar.
214 * @param v scalar
215 * @return scalar as a multiplication of Speed and Duration
216 */
217 public Length multiply(final Duration v)
218 {
219 return new Length(this.si() * v.si(), Length.Unit.SI);
220 }
221
222 /**
223 * Calculate the division of Speed and Duration, which results in a Acceleration scalar.
224 * @param v scalar
225 * @return scalar as a division of Speed and Duration
226 */
227 public Acceleration divide(final Duration v)
228 {
229 return new Acceleration(this.si() / v.si(), Acceleration.Unit.SI);
230 }
231
232 /**
233 * Calculate the division of Speed and Acceleration, which results in a Duration scalar.
234 * @param v scalar
235 * @return scalar as a division of Speed and Acceleration
236 */
237 public Duration divide(final Acceleration v)
238 {
239 return new Duration(this.si() / v.si(), Duration.Unit.SI);
240 }
241
242 /**
243 * Calculate the multiplication of Speed and FlowMass, which results in a Force scalar.
244 * @param v scalar
245 * @return scalar as a multiplication of Speed and FlowMass
246 */
247 public Force multiply(final FlowMass v)
248 {
249 return new Force(this.si() * v.si(), Force.Unit.SI);
250 }
251
252 /**
253 * Calculate the multiplication of Speed and Mass, which results in a Momentum scalar.
254 * @param v scalar
255 * @return scalar as a multiplication of Speed and Mass
256 */
257 public Momentum multiply(final Mass v)
258 {
259 return new Momentum(this.si() * v.si(), Momentum.Unit.SI);
260 }
261
262 /**
263 * Calculate the multiplication of Speed and Momentum, which results in a Energy scalar.
264 * @param v scalar
265 * @return scalar as a multiplication of Speed and Momentum
266 */
267 public Energy multiply(final Momentum v)
268 {
269 return new Energy(this.si() * v.si(), Energy.Unit.SI);
270 }
271
272 /******************************************************************************************************/
273 /********************************************** UNIT CLASS ********************************************/
274 /******************************************************************************************************/
275
276 /**
277 * Speed.Unit encodes the units of the rate of change of a position over time.
278 * <p>
279 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
280 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
281 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
282 * @author Alexander Verbraeck
283 */
284 @SuppressWarnings("checkstyle:constantname")
285 public static class Unit extends AbstractUnit<Speed>
286 {
287 /** The dimensions of Speed: m/s. */
288 public static final SIUnit SI_UNIT = SIUnit.of("m/s");
289
290 /** Meter per second. */
291 public static final Speed.Unit m_s =
292 new Speed.Unit("m/s", "m/s", "meter per second", IdentityScale.SCALE, UnitSystem.SI_DERIVED, null);
293
294 /** The SI or BASE unit. */
295 public static final Speed.Unit SI = m_s;
296
297 /** m/h. */
298 public static final Speed.Unit m_h =
299 new Speed.Unit("m/h", "m/h", "meter per hour", new LinearScale(1.0, 3600.0), UnitSystem.SI_ACCEPTED, null);
300
301 /** km/s. */
302 public static final Speed.Unit km_s =
303 new Speed.Unit("km/s", "km/s", "kilometer per second", new LinearScale(1000.0), UnitSystem.SI_ACCEPTED, null);
304
305 /** km/h. */
306 public static final Speed.Unit km_h = new Speed.Unit("km/h", "km/h", "kilometer per hour",
307 new LinearScale(1000.0, 3600.0), UnitSystem.SI_ACCEPTED, null);
308
309 /** in/s. */
310 public static final Speed.Unit in_s = new Speed.Unit("in/s", "in/s", "inch per second",
311 new LinearScale(Length.Unit.CONST_IN), UnitSystem.IMPERIAL, null);
312
313 /** in/min. */
314 public static final Speed.Unit in_min = new Speed.Unit("in/min", "in/min", "inch per minute",
315 new LinearScale(Length.Unit.CONST_IN, 60.0), UnitSystem.IMPERIAL, null);
316
317 /** in/h. */
318 public static final Speed.Unit in_h = new Speed.Unit("in/h", "in/h", "inch per hour",
319 new LinearScale(Length.Unit.CONST_IN, 3600.0), UnitSystem.IMPERIAL, null);
320
321 /** ft/s. */
322 public static final Speed.Unit ft_s = new Speed.Unit("ft/s", "ft/s", "foot per second",
323 new LinearScale(Length.Unit.CONST_FT), UnitSystem.IMPERIAL, null);
324
325 /** ft/min. */
326 public static final Speed.Unit ft_min = new Speed.Unit("ft/min", "ft/min", "foot per minute",
327 new LinearScale(Length.Unit.CONST_FT, 60.0), UnitSystem.IMPERIAL, null);
328
329 /** ft/h. */
330 public static final Speed.Unit ft_h = new Speed.Unit("ft/h", "ft/h", "foot per hour",
331 new LinearScale(Length.Unit.CONST_FT, 3600.0), UnitSystem.IMPERIAL, null);
332
333 /** mi/s. */
334 public static final Speed.Unit mi_s = new Speed.Unit("mi/s", "mi/s", "mile per second",
335 new LinearScale(Length.Unit.CONST_MI), UnitSystem.IMPERIAL, null);
336
337 /** mi/min. */
338 public static final Speed.Unit mi_min = new Speed.Unit("mi/min", "mi/min", "mile per minute",
339 new LinearScale(Length.Unit.CONST_MI, 60.0), UnitSystem.IMPERIAL, null);
340
341 /** mi/h. */
342 public static final Speed.Unit mi_h = new Speed.Unit("mi/h", "mi/h", "mile per hour",
343 new LinearScale(Length.Unit.CONST_MI, 3600.0), UnitSystem.IMPERIAL, null);
344
345 /** knot = Nautical Mile per hour. */
346 public static final Speed.Unit kt = new Speed.Unit("kt", "knot", Length.Unit.CONST_NM / 3600.0, UnitSystem.OTHER);
347
348 /**
349 * Create a new Speed unit.
350 * @param id the id or main abbreviation of the unit
351 * @param name the full name of the unit
352 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
353 * @param unitSystem the unit system such as SI or IMPERIAL
354 */
355 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
356 {
357 super(id, name, scaleFactorToBaseUnit, unitSystem);
358 }
359
360 /**
361 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
362 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
363 * @param displayAbbreviation the display abbreviation of the unit
364 * @param name the full name of the unit
365 * @param scale the scale to use to convert from this unit to the standard (e.g., SI, BASE) unit
366 * @param unitSystem unit system, e.g. SI or Imperial
367 * @param siPrefix the SI Prefix of this unit
368 */
369 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
370 final UnitSystem unitSystem, final SIPrefix siPrefix)
371 {
372 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem, siPrefix);
373 }
374
375 @Override
376 public SIUnit siUnit()
377 {
378 return SI_UNIT;
379 }
380
381 @Override
382 public Unit getBaseUnit()
383 {
384 return SI;
385 }
386
387 @Override
388 public Speed ofSi(final double si, final UnitInterface<Speed> displayUnit)
389 {
390 return new Speed(si, (Unit) displayUnit, true);
391 }
392
393 @Override
394 public Speed.Unit deriveUnit(final String abbreviation, final String name, final double scaleFactor,
395 final UnitSystem unitSystem)
396 {
397 return (Speed.Unit) super.deriveUnit(abbreviation, name, scaleFactor, unitSystem);
398 }
399
400 @Override
401 public Speed.Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
402 final double scaleFactor, final UnitSystem unitSystem, final SIPrefix siPrefix)
403 {
404 if (getScale() instanceof LinearScale ls)
405 {
406 return new Speed.Unit(textualAbbreviation, displayAbbreviation, name,
407 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem, siPrefix);
408 }
409 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
410 }
411
412 }
413
414 }