Module 4 LinearEquationSolver

in.txt

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+4 4
+0 0 2 0
+0 1 5 1
+0 0 6 0
+0 0 12 0

out.txt

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+Infinite solutions

src/solver/AugmentedMatrix.java

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+package solver;
+
+import java.lang.reflect.Array;
+import java.text.DecimalFormat;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+public class AugmentedMatrix {
+    private Row[] matrix;
+    private String decimalPattern = "#.####";
+
+    // We don't always need swapHistory, so method which uses this field must check whether it is initialized or not.
+    private ArrayList<SwapInfo> swapHistory;
+
+
+    AugmentedMatrix(double[][] matrix) {
+        setMatrix(matrix);
+    }
+
+    AugmentedMatrix() {}
+
+    public void readMatrix(Scanner scanner) throws InputMismatchException {
+        int n = scanner.nextInt();
+        int m = scanner.nextInt();
+        matrix = new Row[n];
+        for (int i = 0; i < n; i++) {
+            matrix[i] = new Row(m);
+            for (int j = 0; j < m; j++) {
+                this.set(i, j, scanner.nextDouble());
+            }
+        }
+    }
+
+    public void set(int i, int j, double value) {
+        matrix[i].set(j, value);
+    }
+
+    public double get(int i, int j) {
+        return matrix[i].get(j);
+    }
+
+
+    public String fancyPrint(String decimalPattern) {
+        if(decimalPattern == null) {
+            decimalPattern = this.decimalPattern;
+        }
+        StringBuilder sb = new StringBuilder();
+        double[] row;
+        for (int i = 0; i < matrix.length; i++) {
+            row = matrix[i].getRow();
+            sb.append("[");
+            for(int j =0; j < row.length; j++) {
+                sb.append(new DecimalFormat(decimalPattern).format(row[j]));
+                sb.append(", ");
+            }
+            sb.delete(sb.length()-2, sb.length());
+            sb.append("]");
+            sb.append("\n");
+        }
+        return sb.toString();
+    }
+
+    @Override
+    public String toString() {
+        return fancyPrint(null);
+    }
+
+    public void swapRows(int firstRowIndex, int secondRowIndex) {
+        Row temp = matrix[firstRowIndex];
+        matrix[firstRowIndex] = matrix[secondRowIndex];
+        matrix[secondRowIndex] = temp;
+    }
+
+    private void addSwapHistoryEntry(int prevIndex, int nextIndex) {
+        // Initialization check
+        if(swapHistory==null) {
+            swapHistory = new ArrayList<>();
+        }
+        swapHistory.add(new SwapInfo(prevIndex, nextIndex));
+    }
+
+    public void clearSwapHistory() {
+        swapHistory.clear();
+    }
+
+    public void swapColumns(int firstColumnIndex, int secondColumnIndex) {
+        swapColumns(firstColumnIndex, secondColumnIndex, true);
+    }
+
+    public void swapColumns(int firstColumnIndex, int secondColumnIndex, boolean writeLog) {
+        double coeff1, coeff2;
+        for(Row row : matrix) {
+            coeff1 = row.get(firstColumnIndex);
+            coeff2 = row.get(secondColumnIndex);
+            row.set(firstColumnIndex, coeff2);
+            row.set(secondColumnIndex, coeff1);
+        }
+        if(writeLog) {
+            addSwapHistoryEntry(firstColumnIndex, secondColumnIndex);
+        }
+    }
+
+    public ArrayList<SwapInfo> getSwapHistory() {
+        return swapHistory;
+    }
+
+    public double[][] getMatrixCopy() {
+        double[][] copy = new double[matrix.length][];
+        for(int i = 0; i < matrix.length; i++) {
+            copy[i] = matrix[i].getRow();
+        }
+        return copy;
+    }
+
+    public void setMatrix(double[][] matrix) {
+        this.matrix = new Row[matrix.length];
+        for(int i = 0; i < matrix.length; i++) {
+            this.matrix[i] = new Row(matrix[i]);
+        }
+    }
+
+    public Row getRow(int index) {
+        return this.matrix[index];
+    }
+
+    public Row getColumnCopy(int index) {
+        int rows = size()[0]; // Number of rows
+        Row col = new Row(rows);
+        for(int i = 0; i < rows; i++) {
+            col.set(i, matrix[i].get(index));
+        }
+        return col;
+    }
+
+
+
+    /**
+     * Get dimensions of Augmented matrix
+     * @return size()[0] - number of rows, size()[1] - number of columns
+     */
+    public int[] size() {
+        int[] size = new int[2];
+        size[0] = matrix.length;
+        // Consider that all rows have the same size, according to the class initialization
+        size[1] = matrix[0].size();
+        return size;
+    }
+
+
+}