Ошибка C# , класс не содержит определения

С горем пополам написал функцию для передачи значений из выпадающего списка в матрицу (matrix_dimensions_changed), но на выходе ошибка с кодом CS1061 - «MainWindow» не содержит определения для «Matrix1_width_SelectionChanged» public partial class MainWindow : Window {

    double[,] Matrix1;
    double[,] Matrix2;
    double[,] Result;
    public MainWindow()
    {
        InitializeComponent();
    }
    // Taking values into grid3 block from result array
    private void initializeGrid(Grid grid, double [,] matrix)
    {
        if (grid != null)
        {
            // Reset the grid before doing anything 
            grid.Children.Clear();
            grid.ColumnDefinitions.Clear();
            grid.RowDefinitions.Clear();
            // Get the dimensions 
            int columns = matrix.GetLength(0);
            int rows = matrix.GetLength(1);
            // Add the correct number of coumns to the grid 
            for (int x = 0; x < columns; x++)
            {
                // GridUnitType.Star - The value is expressed as a weighted proportion of available space
                grid.ColumnDefinitions.Add(new ColumnDefinition() { Width = new GridLength(1, GridUnitType.Star), });
            }
            for (int y = 0; y < rows; y++)
            {
                // GridUnitType.Star - The value is expressed as a weighted proportion of available space
                grid.RowDefinitions.Add(new RowDefinition() { Height = new GridLength(1, GridUnitType.Star), });
            }
            // Fill each cell of the grid with an editable TextBox containing the value from the matrix  
            for (int x = 0; x < columns; x++)
            {
                for (int y = 0; y < rows; y++)
                {
                    double cell = (double)matrix[x, y];
                    TextBox t = new TextBox();
                    t.Text = cell.ToString();
                    t.VerticalAlignment = System.Windows.VerticalAlignment.Center;
                    t.HorizontalAlignment = System.Windows.HorizontalAlignment.Center;
                    t.SetValue(Grid.RowProperty, y);
                    t.SetValue(Grid.ColumnProperty, x);
                    grid.Children.Add(t);
                }
            }
        }
    }
    //Taking values into grid1 and grid2 from matrix1 and matrix2 arrays
    private void getValuesFromGrid(Grid grid, double[,] matrix)
    {
        int columns = grid.ColumnDefinitions.Count;
        int rows = grid.RowDefinitions.Count;
        // Iterate over cells in Grid, copying to matrix array 
        for (int c = 0; c < grid.Children.Count; c++)
        {
            TextBox t = (TextBox)grid.Children[c];
            int row = Grid.GetRow(t);
            int column = Grid.GetColumn(t);
            matrix[column, row] = double.Parse(t.Text);
        }
    }
    private void matrix_dimensions_changed (object Sender, SelectionChangedEventArgs e)
    {
        int m1rows = 1;
        int m2columns = 1;
        int m1columns_m2rows = 1;
        if (Matrix1_width != null) m1columns_m2rows = Matrix1_width.SelectedIndex + 1;
        if (Matrix1_height != null) m1rows = Matrix1_height.SelectedIndex + 1;
        if (Matrix2_width != null) m2columns = Matrix2_width.SelectedIndex + 1;
        Matrix1 = new double[m1columns_m2rows, m1rows];
        Matrix2 = new double[m2columns, m1columns_m2rows];
        Result = new double[m2columns, m1rows];
        Random rand = new Random();
        for (int i=0; i<m1columns_m2rows; i++)
        {
            for (int j=0; j<m1rows; j++)
                Matrix1[i, j] = rand.Next(1, 99);
            for (int j = 0; j < m2columns; j++)
                Matrix2[j, i] = rand.Next(1, 99);
        }
        initializeGrid(grid1, Matrix1);
        initializeGrid(grid2, Matrix2);
        initializeGrid(grid3, Result);
    }
    private void Calculate_Button_Click(object sender, RoutedEventArgs e)
    {
        if (Matrix1_width.SelectedIndex == -1)
        {
            MessageBox.Show("Выберите количество столбцов для первой матрицы!", "Ошибка");
            return;
        }
        if (Matrix1_height.SelectedIndex == -1)
        {
            MessageBox.Show("Выберите количество строк для первой матрицы!", "Ошибка");
            return;
        }
        if (Matrix2_width.SelectedIndex == -1)
        {
            MessageBox.Show("Выберите количество столбцов для второй матрицы", "Ошибка");
            return;
        }
        getValuesFromGrid (grid1, Matrix1);
        getValuesFromGrid (grid2, Matrix2);
        int m1columns_m2rows = Matrix1.GetLength(0);
        int m1rows = Matrix1.GetLength(1);
        int m2columns = Matrix2.GetLength(0);
        for (int row = 0; row < m1rows; row++)
        {
            for (int column = 0; column < m2columns; column++)
            {
                double accumulator = 0;
                for (int cell = 0; cell < m1columns_m2rows; cell++)
                {
                    accumulator = Matrix1[cell, row] * Matrix2[column, cell];
                }
                Result[column, row] = accumulator;
            }
            initializeGrid(grid3, Result);
        }
    }
}

}