Area Of Traingle

Math/AreaOfTriangle.java

@@ -0,0 +1,83 @@
+import java.util.Random;
+
+public class Area_Triangle_Determinants
+{
+    public static double determinant(double A[][], int N)
+    {
+        double det = 0;
+        if (N == 1)
+        {
+            det = A[0][0];
+        } else if (N == 2)
+        {
+            det = A[0][0] * A[1][1] - A[1][0] * A[0][1];
+        } else
+        {
+            det = 0;
+            for (int j1 = 0; j1 < N; j1++)
+            {
+                double[][] m = new double[N - 1][];
+                for (int k = 0; k < (N - 1); k++)
+                {
+                    m[k] = new double[N - 1];
+                }
+                for (int i = 1; i < N; i++)
+                {
+                    int j2 = 0;
+                    for (int j = 0; j < N; j++)
+                    {
+                        if (j == j1)
+                            continue;
+                        m[i - 1][j2] = A[i][j];
+                        j2++;
+                    }
+                }
+                det += Math.pow(-1.0, 1.0 + j1 + 1.0) * A[0][j1]
+                        * determinant(m, N - 1);
+            }
+        }
+        return det;
+    }
+
+    public static void main(String args[])
+    {
+        Random random = new Random();
+        int x1, x2, x3, y1, y2, y3;
+        x1 = random.nextInt(10);
+        x2 = random.nextInt(10);
+        x3 = random.nextInt(10);
+        y1 = random.nextInt(10);
+        y2 = random.nextInt(10);
+        y3 = random.nextInt(10);
+
+        double[][] mat = new double[3][3];
+        mat[0][0] = x1;
+        mat[0][1] = y1;
+        mat[0][2] = 1;
+        mat[1][0] = x2;
+        mat[1][1] = y2;
+        mat[1][2] = 1;
+        mat[2][0] = x3;
+        mat[2][1] = y3;
+        mat[2][2] = 1;
+
+        System.out
+                .println("The matrix formed by the coordinates of the triangle is: ");
+        for (int i = 0; i < 3; i++)
+        {
+            for (int j = 0; j < 3; j++)
+                System.out.print(mat[i][j] + " ");
+            System.out.println();
+        }
+
+        double det = determinant(mat, 3) * 0.5;
+        if (det < 0)
+            System.out.println("The Area of the triangle formed by (" + x1
+                    + "," + y1 + "), (" + x2 + "," + y2 + "), (" + x3 + ","
+                    + y3 + ") = " + (det * -1));
+        else
+            System.out.println("The Area of the triangle formed by (" + x1
+                    + "," + y1 + "), (" + x2 + "," + y2 + "), (" + x3 + ","
+                    + y3 + ") = " + det);
+    }
+}