public static void BottomUpAutoDiffTest()
{
var x = new BottomUpAutoDiff(Math.PI / 4, 1.0);
var y = BottomUpAutoDiff.sin(x);
// sin(x)の微分
//x.setValue(Math.PI / 4);
//x.select();
//y = Math.Sin(x);
Console.WriteLine(2 * y.getdVal());
var x2 = new BottomUpAutoDiff(5.0, 1.0);
var y2 = new BottomUpAutoDiff(1.0, 1.0);
//x = 5.0;
//y = 0.0;
//x.select();
for (int i = 0; i < 10; ++i)
{
y2 = y2 + x2 * x2;
}
// x = 5.0のときのyとdy/dxを出力
Console.WriteLine("{0}, {1}", y2.getValue(), y2.getdVal());
// ニュートン法の実行
var x3 = new BottomUpAutoDiff(2.0, 1.0);
var y3 = new BottomUpAutoDiff(0.0, 1.0);
//x = 2.0; // 適当な初期値
for (int i = 0; i < 10000; ++i)
{
// y = (x-sqrt(2))*(x^2+x+1)
y3.setValue((x3.getValue() - Math.Sqrt(2.0)));// *
//(x3.getValue() * x3.getValue() + x3.getValue() + 1));
// yの値がdoubleの丸め誤差と同程度に小さければ終了
if (y3.getValue() < 1e-15)
{
break;
}
// ニュートン法の更新式で次のxを求める
x3.setValue(x3.getValue() - y3.getValue() / y3.getdVal());
}
// x(=sqrt(2))を出力
Console.WriteLine(x3.getValue());
}
public static BottomUpAutoDiff exp(BottomUpAutoDiff x)
{
return(new BottomUpAutoDiff(Math.Exp(x.val), x.dVal * Math.Exp(x.val)));
}
public static BottomUpAutoDiff sqrt(BottomUpAutoDiff x)
{
return(new BottomUpAutoDiff(Math.Sqrt(x.val), 0.5 * x.dVal / Math.Sqrt(x.val)));
}
public static BottomUpAutoDiff cos(BottomUpAutoDiff x)
{
return(new BottomUpAutoDiff(Math.Cos(x.val), -Math.Sin(x.val)));
}
public static BottomUpAutoDiff log(BottomUpAutoDiff x)
{
return(new BottomUpAutoDiff(Math.Log(x.val), x.dVal / x.val));
}
