source: src/main/java/agents/anac/y2015/agentBuyogV2/flanagan/interpolation/BiCubicSplineFirstDerivative.java

/**********************************************************
*
*   BiCubicSplineFirstDerivative.java
*
*   Class for performing an interpolation on the tabulated
*   function y = f(x1,x2) using a natural bicubic spline
*   Assumes second derivatives at end points = 0 (natural spine)
*   Calculates the interpolated value of y and
*   the first derivatives of y with respect to both x1 and x2
*
*   WRITTEN BY: Dr Michael Thomas Flanagan
*
*   DATE:       January 2010  - modified version of BiCubicSpline (2003 - 2008)
*   UPDATE:
*
*   DOCUMENTATION:
*   See Michael Thomas Flanagan's Java library on-line web page:
*   http://www.ee.ucl.ac.uk/~mflanaga/java/BiCubicSplineFirstDerivative.html
*   http://www.ee.ucl.ac.uk/~mflanaga/java/
*
*   Copyright (c) 2003 - 2010   Michael Thomas Flanagan
*
*   PERMISSION TO COPY:
*
* Permission to use, copy and modify this software and its documentation for NON-COMMERCIAL purposes is granted, without fee,
* provided that an acknowledgement to the author, Dr Michael Thomas Flanagan at www.ee.ucl.ac.uk/~mflanaga, appears in all copies
* and associated documentation or publications.
*
* Redistributions of the source code of this source code, or parts of the source codes, must retain the above copyright notice, this list of conditions
* and the following disclaimer and requires written permission from the Michael Thomas Flanagan:
*
* Redistribution in binary form of all or parts of this class must reproduce the above copyright notice, this list of conditions and
* the following disclaimer in the documentation and/or other materials provided with the distribution and requires written permission from the Michael Thomas Flanagan:
*
* Dr Michael Thomas Flanagan makes no representations about the suitability or fitness of the software for any or for a particular purpose.
* Dr Michael Thomas Flanagan shall not be liable for any damages suffered as a result of using, modifying or distributing this software
* or its derivatives.
*
***************************************************************************************/

package agents.anac.y2015.agentBuyogV2.flanagan.interpolation;

import agents.anac.y2015.agentBuyogV2.flanagan.math.Fmath;

public class BiCubicSplineFirstDerivative{

        private int nPoints = 0;                                    // no. of x1 tabulated points
        private int mPoints = 0;                                    // no. of x2 tabulated points
        private double[][] y = null;                            // y=f(x1,x2) tabulated function
        private double[][] yTranspose = null;                   // transposed tabulated function, y=f(x2,x1)
        private double[] x1 = null;                             // x1 in tabulated function f(x1,x2)
        private double[] x2 = null;                             // x2 in tabulated function f(x1,x2)
        private double[] xMin = new double[2];                  // minimum values of x1 and x2
        private double[] xMax = new double[2];                  // maximum values of x1 and x2
        private BiCubicSplinePartialDerivative cspdY = null;    // BiCubicSplinePartialDerivative instance for entered data
        private BiCubicSplinePartialDerivative cspdYt = null;   // BiCubicSplinePartialDerivative instance for transposed data
        private boolean averageIdenticalAbscissae = false;      // if true: the the ordinate values for identical abscissae are averaged
                                                                // if false: the abscissae values are separated by 0.001 of the total abscissae range;
        private static double potentialRoundingError = 5e-15;   // potential rounding error used in checking wheter a value lies within the interpolation bounds (static value)
        private static boolean roundingCheck = true;            // = true: points outside the interpolation bounds by less than the potential rounding error rounded to the bounds limit (static value)


        // Constructor
        // Constructor with data arrays initialised to arrays x and y
        public BiCubicSplineFirstDerivative(double[] x1, double[] x2, double[][] y){


                this.nPoints=x1.length;
                this.mPoints=x2.length;
                if(this.nPoints!=y.length)throw new IllegalArgumentException("Arrays x1 and y-row are of different length " + this.nPoints + " " + y.length);
                if(this.mPoints!=y[0].length)throw new IllegalArgumentException("Arrays x2 and y-column are of different length "+ this.mPoints + " " + y[0].length);
                if(this.nPoints<3 || this.mPoints<3)throw new IllegalArgumentException("The data matrix must have a minimum size of 3 X 3");

                this.x1 = new double[this.nPoints];
                this.x2 = new double[this.mPoints];
                this.y = new double[this.nPoints][this.mPoints];
                this.yTranspose = new double[this.mPoints][this.nPoints];
                for(int i=0; i<this.nPoints; i++){
                        this.x1[i]=x1[i];
                }
                this.xMin[0] = Fmath.minimum(this.x1);
                this.xMax[0] = Fmath.maximum(this.x1);
                for(int j=0; j<this.mPoints; j++){
                        this.x2[j]=x2[j];
                }
                this.xMin[1] = Fmath.minimum(this.x2);
                this.xMax[1] = Fmath.maximum(this.x2);
                for(int i =0; i<this.nPoints; i++){
                        for(int j=0; j<this.mPoints; j++){
                                this.y[i][j]=y[i][j];
                        }
                }

                // Transpose
                for(int i =0; i<this.nPoints; i++){
                        for(int j=0; j<this.mPoints; j++){
                                this.yTranspose[j][i] = this.y[i][j];
                        }
                }

            // Instantiate CubicSplinePartialDerivative for both y and yTranspose
            this.cspdY = new BiCubicSplinePartialDerivative(x1, x2, y);
            this.cspdYt = new BiCubicSplinePartialDerivative(x2, x1, yTranspose);

        }

        //  METHODS

        // Reset rounding error check option
        // Default option: points outside the interpolation bounds by less than the potential rounding error rounded to the bounds limit
        // This method causes this check to be ignored and an exception to be thrown if any point lies outside the interpolation bounds
        public static void noRoundingErrorCheck(){
            BiCubicSplineFirstDerivative.roundingCheck = false;
            CubicSpline.noRoundingErrorCheck();
        }

        // Reset potential rounding error value
        // Default option: points outside the interpolation bounds by less than the potential rounding error rounded to the bounds limit
        // The default value for the potential rounding error is 5e-15*times the 10^exponent of the value outside the bounds
            // This method allows the 5e-15 to be reset
        public static void potentialRoundingError(double potentialRoundingError){
            BiCubicSplineFirstDerivative.potentialRoundingError = potentialRoundingError;
            CubicSpline.potentialRoundingError(potentialRoundingError);
        }

        // Reset the default handing of identical abscissae with different ordinates
        // from the default option of separating the two relevant abscissae by 0.001 of the range
        // to avraging the relevant ordinates
        public void averageIdenticalAbscissae(){
            this.averageIdenticalAbscissae = true;
            this.cspdY.averageIdenticalAbscissae();
            this.cspdYt.averageIdenticalAbscissae();
        }

            // Get minimum limits
        public double[] getXmin(){
            return this.xMin;
        }

        // Get maximum limits
        public double[] getXmax(){
            return this.xMax;
        }

        // Get limits to x
        public double[] getLimits(){
            double[] limits = {xMin[0], xMax[0], xMin[1], xMax[1]};
            return limits;
        }

        // Display limits to x
        public void displayLimits(){
            System.out.println(" ");
            for(int i=0; i<2; i++){
                System.out.println("The limits to the x array " + i + " are " + xMin[i] + " and " + xMax[i]);
            }
            System.out.println(" ");
        }


        //      Returns an interpolated value of y for a value of x
        //      from a tabulated function y=f(x1,x2)
        public double[] interpolate(double xx1, double xx2){

                double[] interpY = cspdY.interpolate(xx1, xx2);
                double[] interpYt = cspdYt.interpolate(xx2, xx1);
                double averageY = (interpY[0] + interpYt[0])/2.0;
                double[] ret = {averageY, interpY[1], interpYt[1], interpY[0], interpYt[0]};

                return ret;
        }
}