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.numerics.func1d; 39 40 /** 41 * A UnivariateDiffFunction describes a function of a single value (often lambda). Generally, it 42 * should be at least twice differentiable. 43 * 44 * @author Jacob M. Litman 45 * @author Michael J. Schnieders 46 */ 47 public interface UnivariateDiffFunction { 48 49 /** 50 * First derivative at a point. 51 * 52 * @param x a double. 53 * @return f'(x) 54 * @throws java.lang.IllegalArgumentException If f'(x) is undefined at x. 55 */ 56 double firstDerivative(double x) throws IllegalArgumentException; 57 58 /** 59 * N'th order derivative at a point. Should be relatively optional for any order above 2. 60 * 61 * @param x a double. 62 * @param order Derivative order (>= 1) 63 * @return d^nf(x)/dx^n 64 * @throws java.lang.IllegalArgumentException If derivative undefined at x. 65 */ 66 double nthDerivative(double x, int order) throws IllegalArgumentException; 67 68 /** 69 * Second derivative at a point. 70 * 71 * @param x a double. 72 * @return f''(x) 73 * @throws java.lang.IllegalArgumentException If f''(x) is undefined at x. 74 */ 75 double secondDerivative(double x) throws IllegalArgumentException; 76 77 /** 78 * Value at a point 79 * 80 * @param x a double. 81 * @return f(x) 82 * @throws java.lang.IllegalArgumentException If f(x) is undefined at x. 83 */ 84 double valueAt(double x) throws IllegalArgumentException; 85 }