Custom Sorting a grid based on numerical values

        public RadForm1()
        {
            InitializeComponent();

            GridViewDecimalColumn col = new GridViewDecimalColumn("Id");
            this.radGridView1.Columns.Add(col);
            this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;

            this.radGridView1.Rows.Add(5);
            this.radGridView1.Rows.Add(3);
            this.radGridView1.Rows.Add(-1);
            this.radGridView1.Rows.Add(2);
            this.radGridView1.Rows.Add(-1);
            this.radGridView1.Rows.Add(1);
            this.radGridView1.Rows.Add(4);

            this.radGridView1.EnableCustomSorting = true;
            this.radGridView1.CustomSorting += radGridView1_CustomSorting;
        }

        private void radGridView1_CustomSorting(object sender, GridViewCustomSortingEventArgs e)
        { 
            decimal row1Value = (decimal)e.Row1.Cells["Id"].Value;
            decimal row2Value = (decimal)e.Row2.Cells["Id"].Value;
            if (row1Value < 0 && row2Value > 0)
            {
                e.SortResult = 1;
            }
            else if (row2Value < 0 && row1Value > 0)
            {
                e.SortResult = -1;
            }
            else if (row1Value > row2Value)
            {
                e.SortResult = 1;
            }
            else if (row1Value < row2Value)
            {
                e.SortResult = -1;
            }
            else
            {
                e.SortResult = 0;
            }

            if (e.Template.SortDescriptors[0].Direction== ListSortDirection.Descending)
            {
                e.SortResult = e.SortResult*(-1);
            }
        }