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17 package org.apache.commons.math4.legacy.analysis.interpolation;
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19 import org.apache.commons.math4.legacy.exception.DimensionMismatchException;
20 import org.apache.commons.math4.legacy.exception.NoDataException;
21 import org.apache.commons.math4.legacy.exception.NonMonotonicSequenceException;
22 import org.apache.commons.math4.legacy.exception.NumberIsTooSmallException;
23 import org.apache.commons.math4.legacy.core.MathArrays;
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42 public class BicubicInterpolator
43 implements BivariateGridInterpolator {
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48 private final boolean initializeDerivatives;
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55 public BicubicInterpolator() {
56 this(false);
57 }
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67 public BicubicInterpolator(boolean initializeDerivatives) {
68 this.initializeDerivatives = initializeDerivatives;
69 }
70
71
72
73 @Override
74 public BicubicInterpolatingFunction interpolate(final double[] xval,
75 final double[] yval,
76 final double[][] fval)
77 throws NoDataException, DimensionMismatchException,
78 NonMonotonicSequenceException, NumberIsTooSmallException {
79 if (xval.length == 0 || yval.length == 0 || fval.length == 0) {
80 throw new NoDataException();
81 }
82 if (xval.length != fval.length) {
83 throw new DimensionMismatchException(xval.length, fval.length);
84 }
85
86 MathArrays.checkOrder(xval);
87 MathArrays.checkOrder(yval);
88
89 final int xLen = xval.length;
90 final int yLen = yval.length;
91
92
93 final double[][] dFdX = new double[xLen][yLen];
94 final double[][] dFdY = new double[xLen][yLen];
95 final double[][] d2FdXdY = new double[xLen][yLen];
96 for (int i = 1; i < xLen - 1; i++) {
97 final int nI = i + 1;
98 final int pI = i - 1;
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100 final double nX = xval[nI];
101 final double pX = xval[pI];
102
103 final double deltaX = nX - pX;
104
105 for (int j = 1; j < yLen - 1; j++) {
106 final int nJ = j + 1;
107 final int pJ = j - 1;
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109 final double nY = yval[nJ];
110 final double pY = yval[pJ];
111
112 final double deltaY = nY - pY;
113
114 dFdX[i][j] = (fval[nI][j] - fval[pI][j]) / deltaX;
115 dFdY[i][j] = (fval[i][nJ] - fval[i][pJ]) / deltaY;
116
117 final double deltaXY = deltaX * deltaY;
118
119 d2FdXdY[i][j] = (fval[nI][nJ] - fval[nI][pJ] - fval[pI][nJ] + fval[pI][pJ]) / deltaXY;
120 }
121 }
122
123
124 return new BicubicInterpolatingFunction(xval, yval, fval,
125 dFdX, dFdY, d2FdXdY,
126 initializeDerivatives) {
127
128 @Override
129 public boolean isValidPoint(double x, double y) {
130 return !(x < xval[1] ||
131 x > xval[xval.length - 2] ||
132 y < yval[1] ||
133 y > yval[yval.length - 2]);
134 }
135 };
136 }
137 }