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 * Illuminance is the luminous flux incident on a surface per unit area, measured in lux (lx).
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 Illuminance extends Quantity<Illuminance>
22 {
23 /** Constant with value zero. */
24 public static final Illuminance ZERO = ofSi(0.0);
25
26 /** Constant with value one. */
27 public static final Illuminance ONE = ofSi(1.0);
28
29 /** Constant with value NaN. */
30 @SuppressWarnings("checkstyle:constantname")
31 public static final Illuminance NaN = ofSi(Double.NaN);
32
33 /** Constant with value POSITIVE_INFINITY. */
34 public static final Illuminance POSITIVE_INFINITY = ofSi(Double.POSITIVE_INFINITY);
35
36 /** Constant with value NEGATIVE_INFINITY. */
37 public static final Illuminance NEGATIVE_INFINITY = ofSi(Double.NEGATIVE_INFINITY);
38
39 /** Constant with value MAX_VALUE. */
40 public static final Illuminance POS_MAXVALUE = ofSi(Double.MAX_VALUE);
41
42 /** Constant with value -MAX_VALUE. */
43 public static final Illuminance NEG_MAXVALUE = ofSi(-Double.MAX_VALUE);
44
45 /** */
46 private static final long serialVersionUID = 600L;
47
48 /**
49 * Instantiate a Illuminance 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 Illuminance(final double valueInUnit, final Illuminance.Unit unit)
54 {
55 super(valueInUnit, unit);
56 }
57
58 /**
59 * Return a Illuminance instance based on an SI value.
60 * @param si the si value
61 * @return the Illuminance instance based on an SI value
62 */
63 public static Illuminance ofSi(final double si)
64 {
65 return new Illuminance(si, Illuminance.Unit.SI);
66 }
67
68 @Override
69 public Illuminance instantiateSi(final double si)
70 {
71 return ofSi(si);
72 }
73
74 @Override
75 public SIUnit siUnit()
76 {
77 return Illuminance.Unit.SI_UNIT;
78 }
79
80 /**
81 * Returns a Illuminance representation of a textual representation of a value with a unit. The String representation that
82 * can 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 Illuminance
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 Illuminance valueOf(final String text)
90 {
91 return Quantity.valueOf(text, ZERO);
92 }
93
94 /**
95 * Returns a Illuminance 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 Illuminance of(final double valueInUnit, final String unitString)
103 {
104 return Quantity.of(valueInUnit, unitString, ZERO);
105 }
106
107 @Override
108 public Illuminance.Unit getDisplayUnit()
109 {
110 return (Illuminance.Unit) super.getDisplayUnit();
111 }
112
113 /**
114 * Calculate the division of Illuminance and Illuminance, which results in a Dimensionless quantity.
115 * @param v quantity
116 * @return quantity as a division of Illuminance and Illuminance
117 */
118 public final Dimensionless divide(final Illuminance v)
119 {
120 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
121 }
122
123 /**
124 * Calculate the multiplication of Illuminance and Area, which results in a LuminousFlux scalar.
125 * @param v scalar
126 * @return scalar as a multiplication of Illuminance and Area
127 */
128 public final LuminousFlux multiply(final Area v)
129 {
130 return new LuminousFlux(this.si() * v.si(), LuminousFlux.Unit.SI);
131 }
132
133 /******************************************************************************************************/
134 /********************************************** UNIT CLASS ********************************************/
135 /******************************************************************************************************/
136
137 /**
138 * Illuminance.Unit encodes the units of illuminance.
139 * <p>
140 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
141 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
142 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
143 * @author Alexander Verbraeck
144 */
145 @SuppressWarnings("checkstyle:constantname")
146 public static class Unit extends AbstractUnit<Illuminance.Unit, Illuminance>
147 {
148 /** The dimensions of illuminance: srcd/m2. */
149 public static final SIUnit SI_UNIT = SIUnit.of("srcd/m2");
150
151 /** Lux. */
152 public static final Illuminance.Unit lx = new Illuminance.Unit("lx", "lux", 1.0, UnitSystem.SI_DERIVED);
153
154 /** The SI or BASE unit. */
155 public static final Illuminance.Unit SI = lx.generateSiPrefixes(false, false);
156
157 /** mlux. */
158 public static final Illuminance.Unit mlx = Units.resolve(Illuminance.Unit.class, "mlx");
159
160 /** mulux. */
161 public static final Illuminance.Unit mulx = Units.resolve(Illuminance.Unit.class, "mulx");
162
163 /** klux. */
164 public static final Illuminance.Unit klx = lx.deriveUnit("klx", "kilolux", 1.0E3, UnitSystem.SI_DERIVED);
165
166 /** phot. */
167 public static final Illuminance.Unit ph = klx.deriveUnit("ph", "phot", 10.0, UnitSystem.CGS);
168
169 /** nox. */
170 public static final Illuminance.Unit nx = mlx.deriveUnit("nx", "nox", 1.0, UnitSystem.OTHER);
171
172 /**
173 * Create a new Illuminance unit.
174 * @param id the id or main abbreviation of the unit
175 * @param name the full name of the unit
176 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
177 * @param unitSystem the unit system such as SI or IMPERIAL
178 */
179 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
180 {
181 super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
182 }
183
184 /**
185 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
186 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
187 * @param displayAbbreviation the display abbreviation of the unit
188 * @param name the full name of the unit
189 * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
190 * @param unitSystem unit system, e.g. SI or Imperial
191 */
192 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
193 final UnitSystem unitSystem)
194 {
195 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
196 }
197
198 @Override
199 public SIUnit siUnit()
200 {
201 return SI_UNIT;
202 }
203
204 @Override
205 public Unit getBaseUnit()
206 {
207 return SI;
208 }
209
210 @Override
211 public Illuminance ofSi(final double si)
212 {
213 return Illuminance.ofSi(si);
214 }
215
216 @Override
217 public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
218 final double scaleFactor, final UnitSystem unitSystem)
219 {
220 if (getScale() instanceof LinearScale ls)
221 {
222 return new Illuminance.Unit(textualAbbreviation, displayAbbreviation, name,
223 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
224 }
225 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
226 }
227
228 }
229 }