Multiplying a matrix by a c# WPF vector

It is necessary to multiply the matrix by the vector, while full manipulation of the matrix should be available, how much I fight does not work, help, who knows how?

public partial class Window1 : Window
{
    //Matrix A= new Matrix()
    ObservableCollection<ObservableCollection<int>> matrix = new ObservableCollection<ObservableCollection<int>>();
    ObservableCollection<ObservableCollection<int>> vector = new ObservableCollection<ObservableCollection<int>>();
    //ObservableCollection<ObservableCollection<int>> matrix1 = new ObservableCollection<ObservableCollection<int>>();
    ObservableCollection<ObservableCollection<int>> matrix1 = new ObservableCollection<ObservableCollection<int>>();
    Vector vectorr=new Vector(1, numberrow);
    Random rnd = new Random();
    static byte numberrow;
    static byte numbercolumn;//(countColumn)

    public Window1()
    {
        InitializeComponent();
        dgMatrix.ItemsSource=matrix;
    }

    void DataGrid_LoadingRow(object sender, DataGridRowEventArgs e)
    {
        e.Row.Header=e.Row.GetIndex()+1;
    }

    private void CreateDataGrid(DataGrid dgMatrix, int numbercolumn)
    {
        dgMatrix.Columns.Clear();
        if(numbercolumn>0)
        {
            for(int i=0;i<numbercolumn;i++)
            {
                DataGridTextColumn column = new DataGridTextColumn
                {
                    Header = (i+1).ToString(),
                    Binding = new Binding(string.Format("[{0}]",i))
                };
                dgMatrix.Columns.Add(column);
            }
        }
    }


    /*  private ObservableCollection<ObservableCollection<int>> CreateVector(int numberrow, int numbercolumn)
    {
        vector.Clear();

        if(numberrow>0 && numbercolumn>0)
        {
            for(int i =0; i <numberrow;i++)
            {
                vector[i].Add(rnd.Next(-10,10));
            }
        }
        return vector;
    }*/

    private ObservableCollection<ObservableCollection<int>> CreateMatrix(int numberrow, int numbercolumn)
    {
        matrix.Clear();
        if(numberrow>0 && numbercolumn>0)
        {
            for(int i =0; i <numberrow;i++)
            {
                matrix.Add(new ObservableCollection<int>());

                for(int j=0;j<numbercolumn;j++)

                    matrix[i].Add(rnd.Next(-10,10));
            }
        }
        return matrix;
    }


    void button1_Click(object sender, RoutedEventArgs e)
    {

        otvet.Clear();
        if(!byte.TryParse(TextRow.Text, out numberrow)||!byte.TryParse(TextColumn.Text, out numbercolumn))
        {
            MessageBox.Show("Была установлена неправильная размерность!","Информация", MessageBoxButton.OK,MessageBoxImage.Error);
        }
        CreateMatrix(numberrow, numbercolumn);
        //CreateVector(numberrow, numbercolumn);

        CreateDataGrid(dgMatrix, numbercolumn);
        dgMatrix.Visibility=Visibility.Visible;

    }



    void TextRow_GotFocus(object sender, RoutedEventArgs e)
    {
        TextRow.Clear();
    }

    void TextColumn_GotFocus(object sender, RoutedEventArgs e)
    {
        TextColumn.Clear();
    }
    void DgMatrix_TextInput(object sender, TextCompositionEventArgs e)
    {
        MessageBox.Show("Были введены недопустимые символы! Введите число!","Информация", MessageBoxButton.OK,MessageBoxImage.Error);
    }
    void MenuItem_Click4(object sender, RoutedEventArgs e)
    {
        MessageBoxResult result = MessageBox.Show("Вариант 45. Найти максимальное собственное число матрицы, методом сколярных произведений", "Задание", MessageBoxButton.OK, MessageBoxImage.None);

    }
    void MenuItem_Click5(object sender, RoutedEventArgs e)
    {
        MessageBoxResult result = MessageBox.Show("Разработано студентом первого курса, группы БПИ-111, Чуриловым Андреем Алексеевичем, в качестве практической работы", "Задание", MessageBoxButton.OK, MessageBoxImage.None);

    }
    void button2_Click(object sender, RoutedEventArgs e)
    {
        double lmbd=0;
        if (otvet.Text==String.Empty)
        {
            otvet.Clear();
            int B=0;
            //Vector x = new Vector(1,numberrow);
            int j=0;
            int i=0;
            //var Y=VectorY(matrix, vector);//считаем Y
            var Y = VectorY(matrix, vector);
            lmbd+=matrix1[i][j]*vector[i][j];


            otvet.Text+=8;
        }
    }

    private ObservableCollection<ObservableCollection<int>> VectorY(ObservableCollection<ObservableCollection<int>> matrix, ObservableCollection<ObservableCollection<int>> vector)
    {//процесс умножения
        var matrix1 = new ObservableCollection<ObservableCollection<int>>();
        int num = 0;
        for (int i = 0; i < matrix.Count-1; i++)
        {
            matrix1.Add(new ObservableCollection<int>());
            for (int j = 0; j < matrix[i].Count-1; j++)
            {
                for (int k = 0; k < vector[i].Count-1; k++)
                {
                    num += matrix[i][k] * vector[k][j];
                }
                matrix1[i].Add(num);
                num=0;
            }
        }
        return matrix1;
    }

}