using System;
using System.Runtime.InteropServices;/* Provides mappings between C# and native code */

namespace NumericalAlgorithmsGroup
{
  class Simplex
    {
      /* Delegate object, note that:
          1) the scalar parameter is 'ref' 
          2) IntPtr is equivalent to the C void pointer. During a callback Fortran passes a void pointer
             as the parameter to C#. The memory pointed to by the IntPtr is reclaimed using Marshal.copy
      */

	public delegate void  NAG_E04CC_FUNCT (ref int n, IntPtr xc_ptr, ref double fc);
	public delegate void  NAG_E04CC_MONIT (ref double fmin, ref double fmax,
					       IntPtr sim_ptr,/* double [,] sim,*/
					       ref int n, ref int ldsim, ref int ncall);
	static int imonit = 0;
	[DllImport("FLDLL214Z_nag.dll")] /* Import from DLL, the C# compiler provides a rudimentry check of the signature */
	  public static extern void E04CCF(ref int n, double [] x, ref double f, ref double tol,
					   ref int iw, double [] w1, double [] w2, double [] w3,
					   double [] w4, double [] w5, double [] w6,
					   NAG_E04CC_FUNCT funct, NAG_E04CC_MONIT monit,
					   ref int maxcal, ref int ifail);
	   public static void Main()
	  {
	    /* Create delegate objects */
	    NAG_E04CC_FUNCT FUNCT = new NAG_E04CC_FUNCT(myfunct);
	    NAG_E04CC_MONIT MONIT = new NAG_E04CC_MONIT(mymonit);
	    int n = 2;
	    double [] x = {-1.0, 1.0};
	    double f=99.0;
	    double tol = 1.0e-6;
	    int iw = n+1;
	    double [] w1 = new double[n];
	    double [] w2 = new double[n];
	    double [] w3 = new double[n];
	    double [] w4 = new double[n];
	    double [] w5 = new double[iw];
	    double [] w6 = new double[iw*n];
	    int ifail = 1;
	    int maxcal = 100;
	//    imonit = 1;
	    E04CCF(ref n, x, ref f, ref tol, ref iw, w1, w2, w3, w4, w5, w6,
		   FUNCT, MONIT, ref maxcal, ref ifail);
	    if (ifail != 0)
	      {
		// throw exception
	      }
	    Console.WriteLine("Final value = {0, 7:f4}\n at the point {1, 7:f4}, {2, 7:f4}", f, x[0], x[1]);
	  }
	public static void myfunct(ref int n, IntPtr xc_ptr, ref double fc)
	  {
	    double [] xc = new double[n];
	    Marshal.Copy( xc_ptr, xc, 0, n );
	    fc = Math.Exp(xc[0]) * (xc[0] * 4.0 * (xc[0] + xc[1]) +
			       xc[1] * 2.0 * (xc[1] + 1.0) + 1.0);
	  }
	public static void mymonit(ref double fmin, ref double fmax, IntPtr sim_ptr,/* double [,] sim,*/
				   ref int n, ref int ldsim, ref int ncall)
	  {
	    double [] sim = new double[ldsim*n];
	    Marshal.Copy( sim_ptr, sim, 0, ldsim*n );/* Marshal.copy does not allow the type of sim to be [,] */
	    if (imonit != 0 )
	      {
		Console.WriteLine("After {0} calls, the Simplex is ", ncall);
		for (int i=0; i<ldsim; i++)
		  {
		    for (int j=0; j<n; j++)
		      {
			/* Note the expression required to access the elements of sim */
			Console.Write("{0, 12:F4}", sim[j*ldsim+i]);
		      }
		    Console.WriteLine("");
		  }
	      }
	  }
    }
}