//绘制曲线
public void DrawCurve(Coefficient[] curveCoX, Coefficient[] curveCoY, int period, ref Bitmap bmp, int accuracy)
{
double x, y;
int intx, inty;
double tempDouble;
for (int i = 0; i <= period * accuracy - 1; i++)
{
if (null == curveCoX) continue;
x = curveCoX[0].cos / 2;
y = curveCoY[0].cos / 2;
for (int j = 1; j <= curveCoX.Length - 1; j++)
{
tempDouble = 2 * Math.PI * j * i / accuracy;
tempDouble /= period;
x += curveCoX[j].cos * Math.Cos(tempDouble);
x += curveCoX[j].sin * Math.Sin(tempDouble);
tempDouble = 2 * Math.PI * j * i / accuracy;
tempDouble /= period;
y += curveCoY[j].cos * Math.Cos(tempDouble);
y += curveCoY[j].sin * Math.Sin(tempDouble);
}
intx = (int)Math.Round(x);
inty = (int)Math.Round(y);
if ((intx < 0) || (intx >= bmp.Width) || (inty < 0) || (inty >= bmp.Height)) continue;
bmp.SetPixel(intx, inty, Color.Black);
}
}
public string FourierExpand(List<BmpPoint> curvePoint, int expansionLevel, int ignoreThres)
{
period = curvePoint.Count;
if (period <= ignoreThres) return "";
curveCoX = new Coefficient[expansionLevel+1];
curveCoY = new Coefficient[expansionLevel+1];
double tempDouble;
for (int i = 0; i <= expansionLevel; i++)
for (int j = 0; j <= period - 1; j++)
{
tempDouble = 2 * Math.PI * i * j;
tempDouble /= period;
curveCoX[i].cos += curvePoint[j].x * Math.Cos(tempDouble);
curveCoX[i].sin += curvePoint[j].x * Math.Sin(tempDouble);
tempDouble = 2 * Math.PI * i * j;
tempDouble /= period;
curveCoY[i].cos += curvePoint[j].y * Math.Cos(tempDouble);
curveCoY[i].sin += curvePoint[j].y * Math.Sin(tempDouble);
}
curveCoX[0].cos *= 2;
curveCoX[0].cos /= period;
curveCoY[0].cos *= 2;
curveCoY[0].cos /= period;
resultText = "x = ";
resultText += Convert.ToString(Math.Round(curveCoX[0].cos, 4));
for (int i = 1; i <= expansionLevel; i++)
{
curveCoX[i].cos *= 2;
curveCoX[i].sin *= 2;
curveCoX[i].cos /= period;
curveCoX[i].sin /= period;
if (Math.Round(curveCoX[i].cos, 4) >= 0) resultText += " +";
else resultText += " ";
resultText += Convert.ToString(Math.Round(curveCoX[i].cos, 4));
resultText += "cos(" + Convert.ToString(i) + "t)";
if (Math.Round(curveCoX[i].sin, 4) >= 0) resultText += " +";
else resultText += " ";
resultText += Convert.ToString(Math.Round(curveCoX[i].sin, 4));
resultText += "sin(" + Convert.ToString(i) + "t)";
resultText += "\r\n";
}
resultText += "y = ";
resultText += Convert.ToString(Math.Round(curveCoY[0].cos, 4));
for (int i = 1; i <= expansionLevel; i++)
{
curveCoY[i].cos *= 2;
curveCoY[i].sin *= 2;
curveCoY[i].cos /= period;
curveCoY[i].sin /= period;
if (Math.Round(curveCoY[i].cos, 4) >= 0) resultText += " +";
else resultText += " ";
resultText += Convert.ToString(Math.Round(curveCoY[i].cos, 4));
resultText += "cos(" + Convert.ToString(i) + "t)";
if (Math.Round(curveCoY[i].sin, 4) >= 0) resultText += " +";
else resultText += " ";
resultText += Convert.ToString(Math.Round(curveCoY[i].sin, 4));
resultText += "sin(" + Convert.ToString(i) + "t)";
resultText += "\r\n";
}
resultText += "\r\n";
return resultText;
}