WPF 拉格朗日插值法简单实现

 <Grid >         <Grid.RowDefinitions>             <RowDefinition Height="*"/>             <RowDefinition Height="auto"/>         </Grid.RowDefinitions>         <ItemsControl Background="White" x:Name="T1" ItemsSource="{Binding    EP }" PreviewMouseLeftButtonUp="T1_PreviewMouseLeftButtonUp">             <ItemsControl.ItemsPanel>                 <ItemsPanelTemplate>                     <Canvas   />                 </ItemsPanelTemplate>             </ItemsControl.ItemsPanel>             <ItemsControl.ItemTemplate>                 <DataTemplate>                     <ContentControl Content="{Binding UI}"/>                 </DataTemplate>             </ItemsControl.ItemTemplate>             <ItemsControl.ItemContainerStyle>                 <Style >                     <Setter Property="Canvas.Top" Value="{Binding Y}"/>                     <Setter Property="Canvas.Left" Value="{Binding X}"/>                 </Style>             </ItemsControl.ItemContainerStyle>         </ItemsControl>         <Button Height="40" Grid.Row="1" Click="Button_Click" Content="draw"/>     </Grid>

namespace 拉格朗日插值 {     public class EPS     {         private double _x;          public double X         {             get { return _x; }             set { _x = value; }         }          private double _y;          public double Y         {             get { return _y; }             set { _y = value; }         }          private Ellipse ellipse;          public Ellipse UI         {             get { return ellipse; }             set { ellipse = value; }         }         public EPS(Point point,bool b=true)         {             UI = new Ellipse             {                 Stroke = new SolidColorBrush(Colors.Silver),                 Fill = new SolidColorBrush(b ? Colors.Red : Colors.Blue),                 Height = b ? 15 : 5,                 Width = b ? 15 : 5             };             Y = point.Y;             X = point.X;         }         public EPS()         {          }     }     /// <summary>     /// MainWindow.xaml 的交互逻辑     /// </summary>     public partial class MainWindow : Window     {         public ObservableCollection<EPS> EP { get; set; }         public MainWindow()         {             InitializeComponent();             EP = new ObservableCollection<EPS>();             DataContext = this;         }          private void T1_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)         {             if (CanDraw)             {                 EP.Clear();                 CanDraw = false;             }             EP.Add(new EPS(e.GetPosition(T1)));             //两点基画法             //if (EP.Count > 3)             //{             //    EP.Clear();                              //}             //if (EP.Count == 2)             //{             //    for (double i = EP[0].X; i < EP[1].X; i+=1)             //    {             //        EP.Add(new EPS(new Point(i,Towpoint(i)),false));             //    }             //}                     }         double Towpoint(double x)         {             var b=                 (EP[0].Y * ((x - EP[1].X) /( EP[0].X - EP[1].X)) )                 +                  (EP[1].Y * ((x - EP[0].X) /( EP[1].X - EP[0].X)));             return b;         }         double MultiPoint(List<EPS> Points,double x)         {             var k = (from item in Points                     let l1 = item.Y                     * (Points.Where(c => c != item).Select(p => x - p.X).Aggregate((a, b) => a * b))                     / (Points.Where(c => c != item).Select(p => item.X - p.X).Aggregate((a, b) => a * b))                     select l1).Sum();                 return k;         }         bool CanDraw;         private void Button_Click(object sender, RoutedEventArgs e)         {             var k = new EPS[EP.Count];             EP.CopyTo(k, 0);             var items = k.ToList();             for (double  i = EP[0].X; i < items.Last().X; i+=5)             {                   EP.Add(new EPS(new Point(i, MultiPoint(items, i)), false));             }             CanDraw = true;         }     } }