Android Open Source - simple-matrix Rational Advanced

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License

The source code is released under:
MIT License
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Java Source Code

package com.alexkang.x3matrixcalculator.calculations;
//from  w  ww.  j a  v  a  2  s.  co m
public class RationalAdvanced {
  
  private static Rational[][] removeElement(Rational[][] list, int x) {
    if (x == 0) {
      Rational[][] listFinal = new Rational[list.length - 1][];
      System.arraycopy(list, 1, listFinal, 0, listFinal.length);
      return listFinal;
    }
    
    Rational[][] rest = new Rational[list.length - 1][];
    System.arraycopy(list, 1, rest, 0, rest.length);
    
    Rational[][] l = removeElement(rest, x-1);
    Rational[][] listFinal = new Rational[list.length - 1][];
    listFinal[0] = list[0];
    
    for (int i=0; i<l.length; i++) {
      listFinal[i+1] = l[i];
    }
    
    return listFinal;
  }
  
  private static Rational[] removeElement2(Rational[] list, int x) {
    if (x == 0) {
      Rational[] listFinal = new Rational[list.length - 1];
      System.arraycopy(list, 1, listFinal, 0, listFinal.length);
      return listFinal;
    }
    
    Rational[] rest = new Rational[list.length - 1];
    System.arraycopy(list, 1, rest, 0, rest.length);
    
    Rational[] l = removeElement2(rest, x-1);
    Rational[] listFinal = new Rational[list.length - 1];
    listFinal[0] = list[0];
    
    for (int i=0; i<l.length; i++) {
      listFinal[i+1] = l[i];
    }
    
    return listFinal;
  }
  
  private static Rational[][] slicer(Rational[][] matrix, int m, int n) {
    Rational[][] matrixM = removeElement(matrix, m);
    Rational[][] matrixFinal = new Rational[matrixM.length][];
    
    for (int i=0; i<matrixM.length; i++) {
      matrixFinal[i] = removeElement2(matrixM[i], n);
    }
    
    return matrixFinal;
  }
  
  private static Rational cofactor(Rational[][] matrix, int m, int n) {
    Rational[][] sub = slicer(matrix, m, n);
    return RationalCalc.mulRat(
        new Rational((int) Math.pow(-1, m+n)), determinant(sub)
        );
  }
  
  private static Rational[][] adjugate(Rational[][] matrix) {
    Rational[][] result = new Rational[matrix.length][matrix[0].length];
    
    for (int i=0; i<matrix.length; i++) {
      for (int j=0; j<matrix[0].length; j++) {
        result[i][j] = cofactor(matrix, i, j);
      }
    }
    
    return RationalBasic.transpose(result);
  }

  public static Rational determinant(Rational[][] matrix) {
    if (matrix.length == 2) {
      return RationalCalc.subRat(
          RationalCalc.mulRat(
              matrix[0][0], matrix[1][1]), 
          RationalCalc.mulRat(
              matrix[0][1], matrix[1][0])
          );
    }
    Rational total = new Rational(0);
    for (int i=0; i<matrix.length; i++) {
      total = RationalCalc.addRat(
          total, RationalCalc.mulRat(
              RationalCalc.mulRat(
                  new Rational((int) Math.pow(-1, i)), 
                  matrix[0][i]), 
              determinant(slicer(matrix, 0, i))
              )
          );
    }
    return total;
  }
  
  static public Rational[][] inverse(Rational[][] matrix) {
    try {
      Rational det = determinant(matrix);
      if (det.getNum() == 0 || det.getDenom() == 0) {
        Rational[][] errorMatrix = new Rational[matrix.length][matrix.length];
        for (int i=0; i<matrix.length; i++) {
          for (int j=0; j<matrix.length; j++) {
            errorMatrix[i][j] = new Rational(0);
          }
        }
        return errorMatrix;
      }
      
      Rational[][] inv = adjugate(matrix);
      Rational oneOverDet = new Rational(
          det.getDenom(),
          det.getNum()
          );
      
      if (matrix.length == 2) {
        inv[0][0] = RationalCalc.mulRat(oneOverDet, matrix[1][1]);
        inv[0][1] = RationalCalc.mulRat(
            oneOverDet,
            RationalCalc.mulRat(
                new Rational(-1),
                matrix[0][1])
                );
        inv[1][0] = RationalCalc.mulRat(
            oneOverDet,
            RationalCalc.mulRat(
                new Rational(-1),
                matrix[1][0])
                );
        inv[1][1] = RationalCalc.mulRat(oneOverDet, matrix[0][0]);
        return inv;
      }
      
      for (int i=0; i<matrix.length; i++) {
        for (int j=0; j<matrix[0].length; j++) {
          inv[i][j] = RationalCalc.mulRat(inv[i][j], oneOverDet);
        }
      }
  
      return inv;
    }
    
    catch (Exception e) {
      Rational[][] errorMatrix = new Rational[matrix.length][matrix.length];
      for (int i=0; i<matrix.length; i++) {
        for (int j=0; j<matrix.length; j++) {
          errorMatrix[i][j] = new Rational(0);
        }
      }
      return errorMatrix;
    }
  }
}
Java Source Code List
