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 * Illuminance is the luminous flux incident on a surface per unit area, measured in lux (lx).
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 Illuminance extends Quantity<Illuminance>
26 {
27 /** Constant with value zero. */
28 public static final Illuminance ZERO = ofSi(0.0);
29
30 /** Constant with value one. */
31 public static final Illuminance ONE = ofSi(1.0);
32
33 /** Constant with value NaN. */
34 @SuppressWarnings("checkstyle:constantname")
35 public static final Illuminance NaN = ofSi(Double.NaN);
36
37 /** Constant with value POSITIVE_INFINITY. */
38 public static final Illuminance POSITIVE_INFINITY = ofSi(Double.POSITIVE_INFINITY);
39
40 /** Constant with value NEGATIVE_INFINITY. */
41 public static final Illuminance NEGATIVE_INFINITY = ofSi(Double.NEGATIVE_INFINITY);
42
43 /** Constant with value MAX_VALUE. */
44 public static final Illuminance POS_MAXVALUE = ofSi(Double.MAX_VALUE);
45
46 /** Constant with value -MAX_VALUE. */
47 public static final Illuminance NEG_MAXVALUE = ofSi(-Double.MAX_VALUE);
48
49 /** */
50 private static final long serialVersionUID = 600L;
51
52 /**
53 * Instantiate a Illuminance 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 Illuminance(final double value, final Illuminance.Unit displayUnit, final boolean useSi)
59 {
60 super(value, displayUnit, useSi);
61 }
62
63 /**
64 * Instantiate a Illuminance 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 Illuminance(final double valueInUnit, final Illuminance.Unit unit)
69 {
70 this(valueInUnit, unit, false);
71 }
72
73 /**
74 * Return a Illuminance instance based on an SI value.
75 * @param si the si value
76 * @return the Illuminance instance based on an SI value
77 */
78 public static Illuminance ofSi(final double si)
79 {
80 return new Illuminance(si, Illuminance.Unit.SI, true);
81 }
82
83 /**
84 * Instantiate a Illuminance 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 Illuminance instance based on an SI value with the given display unit
88 */
89 public static Illuminance ofSi(final double siValue, final Illuminance.Unit displayUnit)
90 {
91 return new Illuminance(siValue, displayUnit, true);
92 }
93
94 @Override
95 public Illuminance instantiateSi(final double siValue, final UnitInterface<Illuminance> displayUnit)
96 {
97 return new Illuminance(siValue, (Illuminance.Unit) displayUnit, true);
98 }
99
100 /**
101 * Returns a Illuminance representation of a textual representation of a value with a unit. The String representation that
102 * can 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 Illuminance
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 Illuminance valueOf(final String text)
110 {
111 return Quantity.valueOf(text, ZERO);
112 }
113
114 /**
115 * Returns a Illuminance 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 Illuminance representation of the value in its unit
119 */
120 public static Illuminance of(final double valueInUnit, final Illuminance.Unit unit)
121 {
122 return new Illuminance(valueInUnit, unit);
123 }
124
125 /**
126 * Returns a Illuminance 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 Illuminance of(final double valueInUnit, final String unitString)
134 {
135 return Quantity.of(valueInUnit, unitString, ZERO);
136 }
137
138 @Override
139 public Illuminance.Unit getDisplayUnit()
140 {
141 return (Illuminance.Unit) super.getDisplayUnit();
142 }
143
144 /**
145 * Calculate the division of Illuminance and Illuminance, which results in a Dimensionless quantity.
146 * @param v quantity
147 * @return quantity as a division of Illuminance and Illuminance
148 */
149 public Dimensionless divide(final Illuminance v)
150 {
151 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
152 }
153
154 /**
155 * Calculate the multiplication of Illuminance and Area, which results in a LuminousFlux scalar.
156 * @param v scalar
157 * @return scalar as a multiplication of Illuminance and Area
158 */
159 public LuminousFlux multiply(final Area v)
160 {
161 return new LuminousFlux(this.si() * v.si(), LuminousFlux.Unit.SI);
162 }
163
164 /******************************************************************************************************/
165 /********************************************** UNIT CLASS ********************************************/
166 /******************************************************************************************************/
167
168 /**
169 * Illuminance.Unit encodes the units of illuminance.
170 * <p>
171 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
172 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
173 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
174 * @author Alexander Verbraeck
175 */
176 @SuppressWarnings("checkstyle:constantname")
177 public static class Unit extends AbstractUnit<Illuminance>
178 {
179 /** The dimensions of illuminance: srcd/m2. */
180 public static final SIUnit SI_UNIT = SIUnit.of("srcd/m2");
181
182 /** Lux. */
183 public static final Illuminance.Unit lx =
184 new Illuminance.Unit("lx", "lx", "lux", IdentityScale.SCALE, UnitSystem.SI_DERIVED, SIPrefixes.getSiPrefix(""));
185
186 /** The SI or BASE unit. */
187 public static final Illuminance.Unit SI = (Unit) lx.generateSiPrefixes(false, false);
188
189 /** mlux. */
190 public static final Illuminance.Unit mlx = Units.resolve(Illuminance.Unit.class, "mlx");
191
192 /** mulux. */
193 public static final Illuminance.Unit mulx = Units.resolve(Illuminance.Unit.class, "mulx");
194
195 /** klux. */
196 public static final Illuminance.Unit klx = Units.resolve(Illuminance.Unit.class, "klx");
197
198 /** phot. */
199 public static final Illuminance.Unit ph = klx.deriveUnit("ph", "ph", "phot", 10.0, UnitSystem.CGS, null);
200
201 /** nox. */
202 public static final Illuminance.Unit nx = mlx.deriveUnit("nx", "nx", "nox", 1.0, UnitSystem.OTHER, null);
203
204 /**
205 * Create a new Illuminance unit.
206 * @param id the id or main abbreviation of the unit
207 * @param name the full name of the unit
208 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
209 * @param unitSystem the unit system such as SI or IMPERIAL
210 */
211 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
212 {
213 super(id, name, scaleFactorToBaseUnit, unitSystem);
214 }
215
216 /**
217 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
218 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
219 * @param displayAbbreviation the display abbreviation of the unit
220 * @param name the full name of the unit
221 * @param scale the scale to use to convert from this unit to the standard (e.g., SI, BASE) unit
222 * @param unitSystem unit system, e.g. SI or Imperial
223 * @param siPrefix the SI Prefix of this unit
224 */
225 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
226 final UnitSystem unitSystem, final SIPrefix siPrefix)
227 {
228 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem, siPrefix);
229 }
230
231 @Override
232 public SIUnit siUnit()
233 {
234 return SI_UNIT;
235 }
236
237 @Override
238 public Unit getBaseUnit()
239 {
240 return SI;
241 }
242
243 @Override
244 public Illuminance ofSi(final double si, final UnitInterface<Illuminance> displayUnit)
245 {
246 return new Illuminance(si, (Unit) displayUnit, true);
247 }
248
249 @Override
250 public Illuminance.Unit deriveUnit(final String abbreviation, final String name, final double scaleFactor,
251 final UnitSystem unitSystem)
252 {
253 return (Unit) super.deriveUnit(abbreviation, name, scaleFactor, unitSystem);
254 }
255
256 @Override
257 public Illuminance.Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation,
258 final String name, final double scaleFactor, final UnitSystem unitSystem, final SIPrefix siPrefix)
259 {
260 if (getScale() instanceof LinearScale ls)
261 {
262 return new Illuminance.Unit(textualAbbreviation, displayAbbreviation, name,
263 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem, siPrefix);
264 }
265 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
266 }
267
268 }
269
270 }