public DFun(double y)
{
this.d0 = y;
Fun f = new Fun(y);
this.d1 = f.ReVal();
this.d2 = -2 * y * this.d1;
this.d3 = -2 * Math.Pow(this.d1,2) - 2 * y * this.d2;
this.d4 = -2 * (this.d0 * this.d3 + 3 * this.d1 * this.d2);
this.d5 = -2 * (this.d0 * this.d4 + 3 * Math.Pow(this.d2, 2) + 4 * this.d3 * this.d1);
this.d6 = -2 * (this.d0 * this.d5 + 5 * this.d4 * this.d1 + 10 * this.d3 * this.d2);
}
public static void Adams(double x0, double y0, double h, int n)
{
double[,] d = new double[2 * n, 2 * n];
for (int i = 0; i <= 4; ++i)
{
d[i, 0] = xx[i];
d[i, 1] = yy[i];
Fun f = new Fun(yy[i]);
d[i, 2] = h * f.ReVal();
}
int m = 3;
for (int j = 3; j <= 6; ++j)
{
for (int i = 0; i <= m; ++i)
d[i, j] = d[i + 1, j - 1] - d[i, j - 1];
--m;
}
for (int i = 5; i <= n + 5; ++i)
{
d[i, 0] = d[i - 1, 0] + h;
double yk = d[i - 1, 1] + d[i - 1, 2] + (d[i - 2, 3] / 2) + (5 * d[i - 3, 4] / 12) + (3 * d[i - 4, 5] / 8) + (251 * d[i - 5, 6] / 720);
d[i, 1] = yk;
Fun f = new Fun(yk);
d[i, 2] = h * f.ReVal();
int j = 3;
for (int l = i - 1; l >= 0; --l)
{
d[l, j] = d[l + 1, j - 1] - d[l, j - 1];
++j;
if (j > 7) break;
}
}
Console.WriteLine("X\t Y\t q\t D1\t D2\t D3\t D4\t");
for (int i = 0; i <= n + 2; ++i)
{
for (int j = 0; j <= 6; ++j)
if (d[i, j] < 0) Console.Write("{0:f6} ", d[i, j]); else Console.Write(" {0:f6} ", d[i, j]);
Console.WriteLine();
}
Console.WriteLine("Rn = {0:f6}", Math.Abs(r[n] - d[n + 2, 1]));
}
public static void Runge(double x0, double y0, double h, int n)
{
double[] x = new double[2 * n];
double[] y = new double[2 * n];
x[0] = x0; y[0] = y0;
Console.WriteLine("X Y");
Console.WriteLine("{0:f6} {1:f6}", x0, y0);
for (int i = 1; i <= n; ++i)
{
Fun f = new Fun(y[i - 1]);
double k1 = h * f.ReVal();
f = new Fun(y[i - 1] + k1 / 2);
double k2 = h * f.ReVal();
f = new Fun(y[i - 1] + k2 / 2);
double k3 = h * f.ReVal();
f = new Fun(y[i - 1] + k3);
double k4 = h * f.ReVal();
x[i] = x[i - 1] + h;
y[i] = y[i - 1] + (k1 + 2 * k2 + 2 * k3 + k4) / 6;
Console.WriteLine("{0:f6} {1:f6}", x[i], y[i]);
}
Console.WriteLine("Rn = {0:f15}", Math.Abs(r[n] - y[n]));
}
public static void Ailer3(double x0, double y0, double h, int n)
{
double[] x = new double[2 * n];
double[] y = new double[2 * n];
x[0] = x0; y[0] = y0;
for (int i = 1; i <= n; ++i)
{
x[i] = x[i - 1] + h;
Fun f1 = new Fun(y[i - 1]);
Fun f = new Fun(y[i - 1] + h * f1.ReVal());
y[i] = y[i - 1] + h/2 * (f1.ReVal() + f.ReVal());
}
DFun g = new DFun(y0);
Console.WriteLine(" X Y R");
for (int i = 0; i <= n; ++i)
{
double ri = Math.Abs(r[i] - y[i]);
if (x[i] < 0) Console.Write("{0:f6}", x[i]); else Console.Write(" {0:f6}", x[i]);
if (y[i] < 0) Console.Write("{0:f6} ", y[i]); else Console.Write(" {0:f6} ", y[i]);
Console.WriteLine("{0:f8}", ri);
}
}