Create Equation-driven Curve (C#)

//---------------------------------------------------------------
// Preconditions:  Open a part document.
//
// Postconditions:
// 1. A 2D sketch is created, and an equation spline of a
//    sine curve is created.
// 2. After the break point, the curve is edited,
//    a cosine curve is created, and the number of points in the
//    spline is reduced.
//----------------------------------------------------------------
using Microsoft.VisualBasic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using SolidWorks.Interop.sldworks;
using SolidWorks.Interop.swconst;
using System.Runtime.InteropServices;
namespace SimplifySketchSpline_CSharp.csproj
{
    partial class SolidWorksMacro
    {

        ModelDoc2 swModel;
        ModelDocExtension swExt;
        SelectionMgr swSelMgr;
        bool boolstatus;
        string y;
        double r1;
        double r2;
        bool rad;
        double ang;
        double xOff;
        double yOff;
        bool LockStart;
        bool LockEnd;

        public void Main()
        {
            swModel = (ModelDoc2)swApp.ActiveDoc;
            swExt = swModel.Extension;
            swSelMgr = (SelectionMgr)swModel.SelectionManager;

            boolstatus = swExt.SelectByID2("Front Plane", "PLANE", 0, 0, 0, false, 0, null, 0);
            swModel.SketchManager.InsertSketch(true);
            swModel.ClearSelection2(true);

            SketchSegment skSegment = default(SketchSegment);
            skSegment = (SketchSegment)swModel.SketchManager.CreateEquationSpline2("", "sin(x)", "", "0", "6.28", false, 0, 0, 0, true,
            true);
            swModel.ViewZoomtofit2();

            System.Diagnostics.Debugger.Break();

            SketchSpline skSpline = default(SketchSpline);
            skSpline = (SketchSpline)skSegment;
            skSpline.GetEquationParameters(out y, out r1, out r2, out rad, out ang, out xOff, out yOff, out LockStart, out LockEnd);

            Debug.Print("y: " + y);
            Debug.Print("range start: " + r1);
            Debug.Print("range end: " + r2);
            Debug.Print("radian?: " + rad);
            Debug.Print("ang offset: " + ang);
            Debug.Print("x offset: " + xOff);
            Debug.Print("y offset: " + yOff);
            Debug.Print("lock start: " + LockStart);
            Debug.Print("lock end: " + LockEnd);

            // Change spline to a cosine curve
            y = "cos(x)";
            skSpline.SetEquationParameters(y, r1, r2, rad, ang, xOff, yOff, LockStart, LockEnd);

            // Reduce the number of points in the spline
            skSpline.Simplify(0.0);

            swModel.SketchManager.InsertSketch(true);

        }



        public SldWorks swApp;

    }
}