// main_funct.java   do an integration method
//                   needs  lib_funct.java   interface
//                   needs  pass_funct.java  implementation


public class main_funct
{
  main_funct()
  {
    double a=pass.a;
    double b=pass.b;
    double sum, y, dx, x;
    int n=20;
	
    System.out.println("main_funct.java running");
    dx = (b-a)/(double)(n-1);
    x = a;
    sum = 0.0;
    for(int i=1; i<n-1; i++) // not end points
    {
      x = x+dx;      
      sum = sum + pass.f(x);
    }
    sum = dx*((pass.f(a)+pass.f(b))/2.0 + sum);
    System.out.println("intergral= "+sum);

    System.out.println("main_funct.java ends");
  }

  public static pass_funct pass=new pass_funct();
  
  public static void main (String[] args)
  {
    new main_funct();
  }
} // end main_funct.java