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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   * Pressure is the force exerted per unit area, measured in pascals (Pa).
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 Pressure extends Quantity<Pressure>
22  {
23      /** Constant with value zero. */
24      public static final Pressure ZERO = Pressure.ofSi(0.0);
25  
26      /** Constant with value one. */
27      public static final Pressure ONE = Pressure.ofSi(1.0);
28  
29      /** Constant with value NaN. */
30      @SuppressWarnings("checkstyle:constantname")
31      public static final Pressure NaN = Pressure.ofSi(Double.NaN);
32  
33      /** Constant with value POSITIVE_INFINITY. */
34      public static final Pressure POSITIVE_INFINITY = Pressure.ofSi(Double.POSITIVE_INFINITY);
35  
36      /** Constant with value NEGATIVE_INFINITY. */
37      public static final Pressure NEGATIVE_INFINITY = Pressure.ofSi(Double.NEGATIVE_INFINITY);
38  
39      /** Constant with value MAX_VALUE. */
40      public static final Pressure POS_MAXVALUE = Pressure.ofSi(Double.MAX_VALUE);
41  
42      /** Constant with value -MAX_VALUE. */
43      public static final Pressure NEG_MAXVALUE = Pressure.ofSi(-Double.MAX_VALUE);
44  
45      /** */
46      private static final long serialVersionUID = 600L;
47  
48      /**
49       * Instantiate a Pressure 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 Pressure(final double valueInUnit, final Pressure.Unit unit)
54      {
55          super(valueInUnit, unit);
56      }
57  
58      /**
59       * Instantiate a Pressure quantity with a unit, expressed as a String.
60       * @param valueInUnit the value, expressed in the unit
61       * @param abbreviation the String abbreviation of the unit in which the value is expressed
62       */
63      public Pressure(final double valueInUnit, final String abbreviation)
64      {
65          this(valueInUnit, Units.resolve(Pressure.Unit.class, abbreviation));
66      }
67  
68      /**
69       * Construct Pressure quantity.
70       * @param value Scalar from which to construct this instance
71       */
72      public Pressure(final Pressure value)
73      {
74          super(value.si(), Pressure.Unit.SI);
75          setDisplayUnit(value.getDisplayUnit());
76      }
77  
78      /**
79       * Return a Pressure instance based on an SI value.
80       * @param si the si value
81       * @return the Pressure instance based on an SI value
82       */
83      public static Pressure ofSi(final double si)
84      {
85          return new Pressure(si, Pressure.Unit.SI);
86      }
87  
88      @Override
89      public Pressure instantiateSi(final double si)
90      {
91          return ofSi(si);
92      }
93  
94      @Override
95      public SIUnit siUnit()
96      {
97          return Pressure.Unit.SI_UNIT;
98      }
99  
100     /**
101      * Returns a Pressure representation of a textual representation of a value with a unit. The String representation that can
102      * 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 Pressure
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 Pressure valueOf(final String text)
110     {
111         return Quantity.valueOf(text, ZERO);
112     }
113 
114     /**
115      * Returns a Pressure based on a value and the textual representation of the unit, which can be localized.
116      * @param valueInUnit the value, expressed in the unit as given by unitString
117      * @param unitString the textual representation of the unit
118      * @return the Scalar representation of the value in its unit
119      * @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
120      * @throws NullPointerException when the unitString argument is null
121      */
122     public static Pressure of(final double valueInUnit, final String unitString)
123     {
124         return Quantity.of(valueInUnit, unitString, ZERO);
125     }
126 
127     @Override
128     public Pressure.Unit getDisplayUnit()
129     {
130         return (Pressure.Unit) super.getDisplayUnit();
131     }
132 
133     /**
134      * Calculate the division of Pressure and Pressure, which results in a Dimensionless quantity.
135      * @param v quantity
136      * @return quantity as a division of Pressure and Pressure
137      */
138     public final Dimensionless divide(final Pressure v)
139     {
140         return new Dimensionless(this.si() / v.si(), Unitless.BASE);
141     }
142 
143     /**
144      * Calculate the multiplication of Pressure and Area, which results in a Force scalar.
145      * @param v scalar
146      * @return scalar as a multiplication of Pressure and Area
147      */
148     public final Force multiply(final Area v)
149     {
150         return new Force(this.si() * v.si(), Force.Unit.SI);
151     }
152 
153     /**
154      * Calculate the multiplication of Pressure and Volume, which results in a Energy scalar.
155      * @param v scalar
156      * @return scalar as a multiplication of Pressure and Volume
157      */
158     public final Energy multiply(final Volume v)
159     {
160         return new Energy(this.si() * v.si(), Energy.Unit.SI);
161     }
162 
163     /******************************************************************************************************/
164     /********************************************** UNIT CLASS ********************************************/
165     /******************************************************************************************************/
166 
167     /**
168      * Pressure.Unit encodes the units of force exerted per unit area.
169      * <p>
170      * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
171      * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
172      * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
173      * @author Alexander Verbraeck
174      */
175     @SuppressWarnings("checkstyle:constantname")
176     public static class Unit extends AbstractUnit<Pressure.Unit, Pressure>
177     {
178         /** The dimensions of pressure: kg/m.s2. */
179         public static final SIUnit SI_UNIT = SIUnit.of("kg/ms2");
180 
181         /** Pascal. */
182         public static final Pressure.Unit Pa = new Pressure.Unit("Pa", "pascal", 1.0, UnitSystem.SI_DERIVED);
183 
184         /** The SI or BASE unit. */
185         public static final Pressure.Unit SI = Pa.generateSiPrefixes(false, false);
186 
187         /** hectopascal. */
188         public static final Pressure.Unit hPa = Units.resolve(Pressure.Unit.class, "hPa");
189 
190         /** kilopascal. */
191         public static final Pressure.Unit kPa = Units.resolve(Pressure.Unit.class, "kPa");
192 
193         /** standard atmosphere. */
194         public static final Pressure.Unit atm = Pa.deriveUnit("atm", "atmosphere (standard)", 101325.0, UnitSystem.OTHER);
195 
196         /** torr. */
197         public static final Pressure.Unit torr = atm.deriveUnit("torr", "Torr", 1.0 / 760.0, UnitSystem.OTHER);
198 
199         /** technical atmosphere = kgf/cm2. */
200         public static final Pressure.Unit at =
201                 Pa.deriveUnit("at", "atmosphere (technical)", Acceleration.Unit.CONST_GRAVITY / 1.0E-4, UnitSystem.OTHER);
202 
203         /** barye = dyne/cm2. */
204         public static final Pressure.Unit Ba = Pa.deriveUnit("Ba", "barye", 1.0E-5 / 1.0E-4, UnitSystem.CGS);
205 
206         /** bar. */
207         public static final Pressure.Unit bar = Pa.deriveUnit("bar", "bar", 1.0E5, UnitSystem.OTHER);
208 
209         /** millibar. */
210         public static final Pressure.Unit mbar = bar.deriveUnit("mbar", "millibar", 1.0E-3, UnitSystem.OTHER);
211 
212         /** cm Hg. */
213         public static final Pressure.Unit cmHg = Pa.deriveUnit("cmHg", "centimeter mercury", 1333.224, UnitSystem.OTHER);
214 
215         /** mm Hg. */
216         public static final Pressure.Unit mmHg = Pa.deriveUnit("mmHg", "millimeter mercury", 133.3224, UnitSystem.OTHER);
217 
218         /** foot Hg. */
219         public static final Pressure.Unit ftHg = Pa.deriveUnit("ftHg", "foot mercury", 40.63666E3, UnitSystem.IMPERIAL);
220 
221         /** inch Hg. */
222         public static final Pressure.Unit inHg = Pa.deriveUnit("inHg", "inch mercury", 3.386389E3, UnitSystem.IMPERIAL);
223 
224         /** kilogram-force per square millimeter. */
225         public static final Pressure.Unit kgf_mm2 = Pa.deriveUnit("kgf/mm2", "kilogram-force per square millimeter",
226                 Acceleration.Unit.CONST_GRAVITY / 1.0E-6, UnitSystem.OTHER);
227 
228         /** pound-force per square foot. */
229         public static final Pressure.Unit lbf_ft2 = Pa.deriveUnit("lbf/ft2", "pound-force per square foot",
230                 Mass.Unit.CONST_LB * Acceleration.Unit.CONST_GRAVITY / (Length.Unit.CONST_FT * Length.Unit.CONST_FT),
231                 UnitSystem.IMPERIAL);
232 
233         /** pound-force per square inch. */
234         public static final Pressure.Unit lbf_in2 = Pa.deriveUnit("lbf/in2", "pound-force per square inch",
235                 Mass.Unit.CONST_LB * Acceleration.Unit.CONST_GRAVITY / (Length.Unit.CONST_IN * Length.Unit.CONST_IN),
236                 UnitSystem.IMPERIAL);
237 
238         /** psi = pound-force per square inch. */
239         public static final Pressure.Unit psi = lbf_in2;
240 
241         /** pieze. */
242         public static final Pressure.Unit pz = Pa.deriveUnit("pz", "pi\u00E8ze", 1000.0, UnitSystem.MTS);
243 
244         /**
245          * Create a new Pressure unit.
246          * @param id the id or main abbreviation of the unit
247          * @param name the full name of the unit
248          * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
249          * @param unitSystem the unit system such as SI or IMPERIAL
250          */
251         public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
252         {
253             super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
254         }
255 
256         /**
257          * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
258          * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
259          * @param displayAbbreviation the display abbreviation of the unit
260          * @param name the full name of the unit
261          * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
262          * @param unitSystem unit system, e.g. SI or Imperial
263          */
264         public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
265                 final UnitSystem unitSystem)
266         {
267             super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
268         }
269 
270         @Override
271         public SIUnit siUnit()
272         {
273             return SI_UNIT;
274         }
275 
276         @Override
277         public Unit getBaseUnit()
278         {
279             return SI;
280         }
281 
282         @Override
283         public Pressure ofSi(final double si)
284         {
285             return Pressure.ofSi(si);
286         }
287 
288         @Override
289         public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
290                 final double scaleFactor, final UnitSystem unitSystem)
291         {
292             if (getScale() instanceof LinearScale ls)
293             {
294                 return new Pressure.Unit(textualAbbreviation, displayAbbreviation, name,
295                         new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
296             }
297             throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
298         }
299 
300     }
301 }