1 // ******************************************************************************
2 //
3 // Title: Force Field X.
4 // Description: Force Field X - Software for Molecular Biophysics.
5 // Copyright: Copyright (c) Michael J. Schnieders 2001-2025.
6 //
7 // This file is part of Force Field X.
8 //
9 // Force Field X is free software; you can redistribute it and/or modify it
10 // under the terms of the GNU General Public License version 3 as published by
11 // the Free Software Foundation.
12 //
13 // Force Field X is distributed in the hope that it will be useful, but WITHOUT
14 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
15 // FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
16 // details.
17 //
18 // You should have received a copy of the GNU General Public License along with
19 // Force Field X; if not, write to the Free Software Foundation, Inc., 59 Temple
20 // Place, Suite 330, Boston, MA 02111-1307 USA
21 //
22 // Linking this library statically or dynamically with other modules is making a
23 // combined work based on this library. Thus, the terms and conditions of the
24 // GNU General Public License cover the whole combination.
25 //
26 // As a special exception, the copyright holders of this library give you
27 // permission to link this library with independent modules to produce an
28 // executable, regardless of the license terms of these independent modules, and
29 // to copy and distribute the resulting executable under terms of your choice,
30 // provided that you also meet, for each linked independent module, the terms
31 // and conditions of the license of that module. An independent module is a
32 // module which is not derived from or based on this library. If you modify this
33 // library, you may extend this exception to your version of the library, but
34 // you are not obligated to do so. If you do not wish to do so, delete this
35 // exception statement from your version.
36 //
37 // ******************************************************************************
38 package ffx.openmm;
39
40 import com.sun.jna.ptr.PointerByReference;
41
42 import static edu.uiowa.jopenmm.OpenMMLibrary.OpenMM_Boolean.OpenMM_True;
43 import static edu.uiowa.jopenmm.OpenMMLibrary.OpenMM_TabulatedFunction_getPeriodic;
44 import static edu.uiowa.jopenmm.OpenMMLibrary.OpenMM_TabulatedFunction_getUpdateCount;
45
46 /**
47 * A TabulatedFunction uses a set of tabulated values to define a mathematical function.
48 * It can be used by various custom forces.
49 * <p>
50 * TabulatedFunction is an abstract class with concrete subclasses for more specific
51 * types of functions. There are subclasses for:
52 *
53 * <ul>
54 * <li>1, 2, and 3 dimensional functions. The dimensionality of a function means
55 * the number of input arguments it takes.</li>
56 * <li>Continuous and discrete functions. A continuous function is interpolated by
57 * fitting a natural cubic spline to the tabulated values. A discrete function is
58 * only defined for integer values of its arguments (that is, at the tabulated points),
59 * and does not try to interpolate between them. Discrete function can be evaluated
60 * more quickly than continuous ones.</li>
61 * </ul>
62 */
63 public abstract class TabulatedFunction {
64
65 /**
66 * The pointer is allocated and deallocated by classes that extend TabulatedFunction.
67 */
68 protected PointerByReference pointer;
69
70 /**
71 * Constructor for TabulatedFunction.
72 *
73 * @param pointer Pointer to the OpenMM TabulatedFunction.
74 * @throws IllegalArgumentException if the pointer is null.
75 */
76 public TabulatedFunction(PointerByReference pointer) {
77 if (pointer == null || pointer.getValue() == null) {
78 throw new IllegalArgumentException("Pointer cannot be null.");
79 }
80 this.pointer = pointer;
81 }
82
83 /**
84 * Destroy the tabulated function.
85 */
86 public abstract void destroy();
87
88 /**
89 * Get the pointer to the OpenMM TabulatedFunction.
90 *
91 * @return The pointer to the OpenMM TabulatedFunction.
92 */
93 public PointerByReference getPointer() {
94 return pointer;
95 }
96
97 /**
98 * Get the periodicity status of the tabulated function.
99 */
100 public boolean getPeriodic() {
101 int periodic = OpenMM_TabulatedFunction_getPeriodic(pointer);
102 return periodic == OpenMM_True;
103 }
104
105 /**
106 * Get the value of a counter that is updated every time setFunctionParameters()
107 * is called. This provides a fast way to detect when a function has changed.
108 */
109 public int getUpdateCount() {
110 return OpenMM_TabulatedFunction_getUpdateCount(pointer);
111 }
112 }