public int SetRow(int index, ComplexList src)
{
for (int i = 0; i < Width; i++)
{
this[index, i] = (i < src.Lenght) ? src[i] : new Complex(0);
}
return(0);
}
public int SetColumn(int index, ComplexList src)
{
for (int i = 0; i < Height; i++)
{
this[i, index] = (i < src.Lenght) ? src[i] : new Complex(0);
}
return(0);
}
public ComplexList GetRow(int index)
{
ComplexList ret = new ComplexList(Width);
for (int i = 0; i < Width; i++)
{
ret[i] = this[index, i];
}
return(ret);
}
public ComplexList GetColumn(int index)
{
ComplexList ret = new ComplexList(Height);
for (int i = 0; i < Height; i++)
{
ret[i] = this[i, index];
}
return(ret);
}
// 快速傅里叶变换
// ComplexList src：数据输入，若长度非2的n次幂，
// 则函数对末尾补零后的数据进行运算
public static ComplexList fft_1D(ComplexList src)
{
int lenght = src.Lenght;
return(fft_core(src, ref lenght, 1));
}
// 快速傅里叶变换
// 作者：死猫
// ComplexList src：数据输入
// ref int lenght：欲变换数据的长度，函数调用后此值更改为实际变换长度
// int flag：区分fft或idft，为1为fft，为-1为idft
private static ComplexList fft_core(ComplexList src, ref int lenght, int flag)
{
//按时间抽取FFT方法(DIT)
//补零后长度
int relog2N = ReLog2N(lenght);
int bitlenghth = relog2N;
int N = 0x01 << bitlenghth;
//重新复制数据，同时进行
// 逆序排放，并补零
int index;
ComplexList Register = new ComplexList(N);
for (int i = 0; i < N; i++)
{
index = ReArrange(i, bitlenghth);
Register[i] = (index < src.Lenght) ? src[index] : new Complex(0);
}
//生成WN表，以免运行时进行重复计算
ComplexList WN = new ComplexList(N / 2);
for (int i = 0; i < N / 2; i++)
{
WN[i] = new Complex(Math.Cos(2 * Math.PI / N * i), -flag * Math.Sin(2 * Math.PI / N * i));
}
//蝶形运算
int Index0, Index1;
Complex temp;
for (int steplenght = 2; steplenght <= N; steplenght *= 2)
{
for (int step = 0; step < N / steplenght; step++)
{
for (int i = 0; i < steplenght / 2; i++)
{
Index0 = steplenght * step + i;
Index1 = steplenght * step + i + steplenght / 2;
temp = Register[Index1] * WN[N / steplenght * i];
Register[Index1] = Register[Index0] - temp;
Register[Index0] = Register[Index0] + temp;
}
}
}
//若为idft
if (-1 == flag)
{
for (int i = 0; i < Register.Lenght; i++)
{
Register[i] /= N;
}
}
//赋值
lenght = N;
/*
* //清理内存
* WN = null;
* temp = null;
* GC.Collect();
*/
//返回
return(Register);
}
// 快速傅里叶变换的逆变换
// ComplexList src：数据输入
// ref int lenght：欲变换数据的长度，函数调用后此值更改为实际变换长度
public static ComplexList idft_1D(ComplexList src, ref int lenght)
{
return(fft_core(src, ref lenght, -1));
}
// 快速傅里叶变换的逆变换
// ComplexList src：数据输入
public static ComplexList idft_1D(ComplexList src)
{
int lenght = src.Lenght;
return(idft_1D(src, ref lenght));
}
