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