View Javadoc
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 = ofSi(0.0);
25  
26      /** Constant with value one. */
27      public static final Pressure ONE = ofSi(1.0);
28  
29      /** Constant with value NaN. */
30      @SuppressWarnings("checkstyle:constantname")
31      public static final Pressure NaN = ofSi(Double.NaN);
32  
33      /** Constant with value POSITIVE_INFINITY. */
34      public static final Pressure POSITIVE_INFINITY = ofSi(Double.POSITIVE_INFINITY);
35  
36      /** Constant with value NEGATIVE_INFINITY. */
37      public static final Pressure NEGATIVE_INFINITY = ofSi(Double.NEGATIVE_INFINITY);
38  
39      /** Constant with value MAX_VALUE. */
40      public static final Pressure POS_MAXVALUE = ofSi(Double.MAX_VALUE);
41  
42      /** Constant with value -MAX_VALUE. */
43      public static final Pressure NEG_MAXVALUE = 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       * Return a Pressure instance based on an SI value.
60       * @param si the si value
61       * @return the Pressure instance based on an SI value
62       */
63      public static Pressure ofSi(final double si)
64      {
65          return new Pressure(si, Pressure.Unit.SI);
66      }
67  
68      @Override
69      public Pressure instantiateSi(final double si)
70      {
71          return ofSi(si);
72      }
73  
74      @Override
75      public SIUnit siUnit()
76      {
77          return Pressure.Unit.SI_UNIT;
78      }
79  
80      /**
81       * Returns a Pressure representation of a textual representation of a value with a unit. The String representation that can
82       * 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 Pressure
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 Pressure valueOf(final String text)
90      {
91          return Quantity.valueOf(text, ZERO);
92      }
93  
94      /**
95       * Returns a Pressure 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 Pressure of(final double valueInUnit, final String unitString)
103     {
104         return Quantity.of(valueInUnit, unitString, ZERO);
105     }
106 
107     @Override
108     public Pressure.Unit getDisplayUnit()
109     {
110         return (Pressure.Unit) super.getDisplayUnit();
111     }
112 
113     /**
114      * Calculate the division of Pressure and Pressure, which results in a Dimensionless quantity.
115      * @param v quantity
116      * @return quantity as a division of Pressure and Pressure
117      */
118     public final Dimensionless divide(final Pressure v)
119     {
120         return new Dimensionless(this.si() / v.si(), Unitless.BASE);
121     }
122 
123     /**
124      * Calculate the multiplication of Pressure and Area, which results in a Force scalar.
125      * @param v scalar
126      * @return scalar as a multiplication of Pressure and Area
127      */
128     public final Force multiply(final Area v)
129     {
130         return new Force(this.si() * v.si(), Force.Unit.SI);
131     }
132 
133     /**
134      * Calculate the multiplication of Pressure and Volume, which results in a Energy scalar.
135      * @param v scalar
136      * @return scalar as a multiplication of Pressure and Volume
137      */
138     public final Energy multiply(final Volume v)
139     {
140         return new Energy(this.si() * v.si(), Energy.Unit.SI);
141     }
142 
143     /******************************************************************************************************/
144     /********************************************** UNIT CLASS ********************************************/
145     /******************************************************************************************************/
146 
147     /**
148      * Pressure.Unit encodes the units of force exerted per unit area.
149      * <p>
150      * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
151      * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
152      * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
153      * @author Alexander Verbraeck
154      */
155     @SuppressWarnings("checkstyle:constantname")
156     public static class Unit extends AbstractUnit<Pressure.Unit, Pressure>
157     {
158         /** The dimensions of pressure: kg/m.s2. */
159         public static final SIUnit SI_UNIT = SIUnit.of("kg/ms2");
160 
161         /** Pascal. */
162         public static final Pressure.Unit Pa = new Pressure.Unit("Pa", "pascal", 1.0, UnitSystem.SI_DERIVED);
163 
164         /** The SI or BASE unit. */
165         public static final Pressure.Unit SI = Pa.generateSiPrefixes(false, false);
166 
167         /** hectopascal. */
168         public static final Pressure.Unit hPa = Units.resolve(Pressure.Unit.class, "hPa");
169 
170         /** kilopascal. */
171         public static final Pressure.Unit kPa = Units.resolve(Pressure.Unit.class, "kPa");
172 
173         /** standard atmosphere. */
174         public static final Pressure.Unit atm = Pa.deriveUnit("atm", "atmosphere (standard)", 101325.0, UnitSystem.OTHER);
175 
176         /** torr. */
177         public static final Pressure.Unit torr = atm.deriveUnit("torr", "Torr", 1.0 / 760.0, UnitSystem.OTHER);
178 
179         /** technical atmosphere = kgf/cm2. */
180         public static final Pressure.Unit at =
181                 Pa.deriveUnit("at", "atmosphere (technical)", Acceleration.Unit.CONST_GRAVITY / 1.0E-4, UnitSystem.OTHER);
182 
183         /** barye = dyne/cm2. */
184         public static final Pressure.Unit Ba = Pa.deriveUnit("Ba", "barye", 1.0E-5 / 1.0E-4, UnitSystem.CGS);
185 
186         /** bar. */
187         public static final Pressure.Unit bar = Pa.deriveUnit("bar", "bar", 1.0E5, UnitSystem.OTHER);
188 
189         /** millibar. */
190         public static final Pressure.Unit mbar = bar.deriveUnit("mbar", "millibar", 1.0E-3, UnitSystem.OTHER);
191 
192         /** cm Hg. */
193         public static final Pressure.Unit cmHg = Pa.deriveUnit("cmHg", "centimeter mercury", 1333.224, UnitSystem.OTHER);
194 
195         /** mm Hg. */
196         public static final Pressure.Unit mmHg = Pa.deriveUnit("mmHg", "millimeter mercury", 133.3224, UnitSystem.OTHER);
197 
198         /** foot Hg. */
199         public static final Pressure.Unit ftHg = Pa.deriveUnit("ftHg", "foot mercury", 40.63666E3, UnitSystem.IMPERIAL);
200 
201         /** inch Hg. */
202         public static final Pressure.Unit inHg = Pa.deriveUnit("inHg", "inch mercury", 3.386389E3, UnitSystem.IMPERIAL);
203 
204         /** kilogram-force per square millimeter. */
205         public static final Pressure.Unit kgf_mm2 = Pa.deriveUnit("kgf/mm2", "kilogram-force per square millimeter",
206                 Acceleration.Unit.CONST_GRAVITY / 1.0E-6, UnitSystem.OTHER);
207 
208         /** pound-force per square foot. */
209         public static final Pressure.Unit lbf_ft2 = Pa.deriveUnit("lbf/ft2", "pound-force per square foot",
210                 Mass.Unit.CONST_LB * Acceleration.Unit.CONST_GRAVITY / (Length.Unit.CONST_FT * Length.Unit.CONST_FT),
211                 UnitSystem.IMPERIAL);
212 
213         /** pound-force per square inch. */
214         public static final Pressure.Unit lbf_in2 = Pa.deriveUnit("lbf/in2", "pound-force per square inch",
215                 Mass.Unit.CONST_LB * Acceleration.Unit.CONST_GRAVITY / (Length.Unit.CONST_IN * Length.Unit.CONST_IN),
216                 UnitSystem.IMPERIAL);
217 
218         /** psi = pound-force per square inch. */
219         public static final Pressure.Unit psi = lbf_in2;
220 
221         /** pieze. */
222         public static final Pressure.Unit pz = Pa.deriveUnit("pz", "pi\u00E8ze", 1000.0, UnitSystem.MTS);
223 
224         /**
225          * Create a new Pressure unit.
226          * @param id the id or main abbreviation of the unit
227          * @param name the full name of the unit
228          * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
229          * @param unitSystem the unit system such as SI or IMPERIAL
230          */
231         public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
232         {
233             super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
234         }
235 
236         /**
237          * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
238          * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
239          * @param displayAbbreviation the display abbreviation of the unit
240          * @param name the full name of the unit
241          * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
242          * @param unitSystem unit system, e.g. SI or Imperial
243          */
244         public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
245                 final UnitSystem unitSystem)
246         {
247             super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
248         }
249 
250         @Override
251         public SIUnit siUnit()
252         {
253             return SI_UNIT;
254         }
255 
256         @Override
257         public Unit getBaseUnit()
258         {
259             return SI;
260         }
261 
262         @Override
263         public Pressure ofSi(final double si)
264         {
265             return Pressure.ofSi(si);
266         }
267 
268         @Override
269         public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
270                 final double scaleFactor, final UnitSystem unitSystem)
271         {
272             if (getScale() instanceof LinearScale ls)
273             {
274                 return new Pressure.Unit(textualAbbreviation, displayAbbreviation, name,
275                         new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
276             }
277             throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
278         }
279 
280     }
281 }