心脏线方程：r=a(1-sinθ)
转换为参数方程
x=2r(sin(t)-sin(2t)/2)
y=2r(cos(t)-cos(2t)/2)
程序代码：
// 在 http://fsharp.net 上了解有关 F# 的更多信息
// 请参阅“F# 教程”项目以获取更多帮助。
//DLL如果没有则需要手动添加引用
open System.Drawing
open System.Windows.Forms
[<EntryPoint>]
let main argv =
System.Console.WriteLine("心脏线绘制程序 By Tsybius")
System.Console.WriteLine("2014年9月21日 21:53:52")
System.Console.WriteLine("=============================\n")
System.Console.WriteLine("正在构建窗体（Form）")
//添加窗体Form
let frmHeart = new Form()
//设置窗体属性
frmHeart.Name <- "frmHeart"
frmHeart.Text <- "心脏线 r=a(1-sinθ)"
frmHeart.AutoScaleDimensions <- new System.Drawing.SizeF(6.0f, 12.0f)
frmHeart.AutoScaleMode <- System.Windows.Forms.AutoScaleMode.Font
frmHeart.ClientSize <- new System.Drawing.Size(480, 458)
frmHeart.FormBorderStyle <- System.Windows.Forms.FormBorderStyle.Fixed3D
frmHeart.StartPosition <- System.Windows.Forms.FormStartPosition.CenterScreen
//frmHeart.BackColor <- System.Drawing.SystemColors.ActiveCaption
frmHeart.MaximizeBox <- false
frmHeart.MinimizeBox <- false
frmHeart.ShowIcon <- false
frmHeart.TopMost <- true
System.Console.WriteLine("正在构建图片框（PictureBox）")
//设立图画框PictureBox
let picImage = new System.Windows.Forms.PictureBox()
picImage.Dock <- System.Windows.Forms.DockStyle.Fill
picImage.Location <- new System.Drawing.Point(0, 0)
picImage.Name <- "picImage"
picImage.Size <- new System.Drawing.Size(480, 458)
picImage.BackColor <- System.Drawing.SystemColors.ActiveCaption
picImage.Image <- new Bitmap(picImage.Width, picImage.Height)
frmHeart.Controls.Add(picImage)
System.Console.WriteLine("开始绘制图像")
//绘制图像
let grph: Graphics = Graphics.FromImage(picImage.Image)
System.Console.WriteLine("绘制横轴")
//横轴
grph.DrawLine((new Pen(Brushes.Green, 5.0f)), 30, 135, 450, 135)
grph.FillPolygon(Brushes.Green, //左侧箭头
[| new Point(60, 125);
new Point(10, 135);
new Point(60, 145);
new Point(90, 135) |]);
grph.FillPolygon(Brushes.Green, //右侧箭头
[| new Point(420, 125);
new Point(470, 135);
new Point(420, 145);
new Point(390, 135) |]);
System.Console.WriteLine("绘制纵轴")
//纵轴
grph.DrawLine((new Pen(Brushes.Green, 5.0f)), 240, 30, 240, 428)
grph.FillPolygon(Brushes.Green, //上侧箭头
[| new Point(240, 20);
new Point(225, 30);
new Point(240, 70);
new Point(255, 30) |]);
grph.FillPolygon(Brushes.Green, //下侧箭头
[| new Point(240, 370);
new Point(225, 400);
new Point(240, 445);
new Point(255, 400) |]);
System.Console.WriteLine("绘制心脏线")
//心脏绘制开始
let r = 50.0
let funt (t: int) = (float)t * 2.0 * 3.1416 / 10000.0 : float
//横坐标
let funx (t: float) =
-1 * (int)(2.0 * r * (sin(t) - sin(2.0 * t) / 2.0 + 0.5)) : int
//纵坐标
let funy (t: float) =
-1 * (int)(2.0 * r * (cos(t) - cos(2.0 * t) / 2.0 + 0.5)) : int
let p: Point[] =
[| for t in 0 .. 10000 ->
new Point(funx(funt(t)) + 290, funy(funt(t)) + 235) |]
grph.FillPolygon(Brushes.Pink, p)
grph.DrawPolygon((new Pen(Brushes.Red, 5.0f)), p)
//心脏绘制结束
System.Console.WriteLine("绘制字符")
let brushstr1 = new SolidBrush(Color.Blue)
let fontstr1 = new Font("Consolas", 24.0f)
grph.DrawString("CARDIOID", fontstr1, brushstr1, 160.0f, 175.0f )
grph.DrawString("r=a(1-sinθ)", fontstr1, brushstr1, 140.0f, 215.0f )
System.Console.WriteLine("绘制签名：Tsybius")
let brushstr2 = new SolidBrush(Color.White)
let fontstr2 = new Font("Consolas", 24.0f)
grph.DrawString("TSYBIUS 2014/9/21", fontstr2, brushstr2, 150.0f, 405.0f )
System.Console.WriteLine("打开窗体")
//打开窗体
let result = frmHeart.ShowDialog()
System.Console.WriteLine()
//按任意键继续（退出）
System.Console.WriteLine("按任意键继续")
let temp = System.Console.ReadKey()
let temp = System.Console.Write("\b\t") //删除按下的“任意键”字符
0 // 返回整数退出代码
运行示例：
END