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Need help for trapezoidal rule java code

Need help for trapezoidal rule java code

Hi guys. Need help...
I tried running the code for trapezoidal rule. It's my project in Numerical Methods, here's the code:


CODE --> Java

static double trapezoidRule (int size, double[] x, double[] y)
   {  double sum = 0.0,

      for ( int k = 1; k < size; k++ )
      {//Trapezoid rule:  1/2 h * (f0 + f1)
         increment = 0.5 * (x[k]-x[k-1]) * (y[k]+y[k-1]);
         sum += increment;
      return sum;

   public static void main ( String[] args ) throws Exception
   {  String   fileName = args.length > 0 ? args[0] : "InpData.txt";
      Scanner  inp = new Scanner(new File(fileName));
      int      k, size;
      double[] x, y;
      double   integral;

      size = inp.nextInt();
      System.out.println ("Number of points:  " + size);

      x = new double[size];
      y = new double[size];

      for ( k = 0; k < size; k++ )
      {  x[k] = inp.nextDouble();
         y[k] = inp.nextDouble();
      integral = trapezoidRule (size, x, y);
      System.out.printf ("Integral:  %4.4f\n", integral);
      System.out.printf ("Check:  log(%2.2f) = %8.8f\n",
                         x[size-1], Math.log(x[size-1]) );

It cannot be compiled and I always get FileNotFoundException. I found on javadocs that this will be thrown when a file with the path name does not exist. Please help. Thanks!

RE: Need help for trapezoidal rule java code


Really missing the class declaration line or just a copy-pasting mistake ?


RE: Need help for trapezoidal rule java code

Copy paste mistake dude. Any thoughts in how to get rid with FileNotFoundException error? Still can't find answers until now...

RE: Need help for trapezoidal rule java code


  • Are you passing it input file name when running it ?
    • If yes, what is that file name ?
  • Does the input file ( with the name you pass in parameter or the default InpData.txt ) exist ?


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