Question

pretty straight-forward question, I get an error I don’t know how to solve, in Visual C# Express, when I call the Romberg function in my main (I provided the error message at the appropriate line). I tried using this.Romberg too but it didn’t help. What should I do differently?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Romberg2
{
    class test
    {
        // the function
        double f(double x)
        {
            double f;
            f=8*(Math.Sqrt(1-x*x)-x);
            return f;
        }

        // The Integration function
        void Romberg(double a, double b, int n, double[,] R)
        {
            int i, j, k;
            double h, sum;

            h = b - a;
            R[0,0]=(h/2)*(f(a)+f(b));

            for (i=1; i<=n; i++)
            {
                h=h/2;
                sum=0;

                for (k=1; k <= (Math.Pow(2.0,i)-1); k +=2)
                    sum +=f(a+k*h);

                R[i,0]=R[i-1,0]/2+sum*h;

                for(j=1; j<=i; j++)
                    R[i,j]=R[i,j-1]+(R[i,j-1]-R[i-1,j-1])/(Math.Pow(4.0,j)-1);
            }
        }

        static void main(int argc, char [] argv)
        {
            double[,] R = new double [10,10];
            int n=5, digits=13;
            double a=0, b=1/Math.Sqrt(2.0);

            // Call the integrating function
            Romberg(a, b, n, R);//ERROR: An object reference is required for the non-static field, method, or property

            // Printout the diagram
            for(int i=0; i<n; i++)
            {
                for(int j=0; j<=i; j++)
                {
                    Console.WriteLine(R[i,j] + " ");
                }
                Console.WriteLine("\n");
            }

        }
    }
}

Answer 1

Three problems:

1) Main is not the correct format. It needs to be in one of these formats:

static void Main() {...} 
static void Main(string[] args) {... } 
static int Main() {...} 
static int Main(string [] args) {...}

Just change it to ‘static void Main()’

2) Make Romberg method static

static void Romberg(double a, double b, int n, double[,] R)

3) Make f method static:

static double f(double x)