I am having problems with my FFT in c# - fft

Question

Does Microsoft have a good FFT that I can use ?
so I made my owe FFT and it work from some case but now all...
like if I get it
f(t) =10*sin(2*pi *3000*t) + 20*sin(1000* 2* PI* t)
it will work but if I add
+ 5*sin(2*pi*100*T) is start acting fun?
now in Matlab it works good but not in my close, also my fft only seem to return the right numbers in the Image not so much in the real...
here is my code:
enter code here
public struct polar1
{
public double real;
public double img;
};
private float Fs;
private int N;
private polar1 [] F;
private int R;
public DSPclass(float[] DSP1,int f1)
{
N = DSP1.Length;
R = DSP1.Length;
F = new polar1[N];
Fs = (float)f1;
}
public void FFT1(float[] DSP1)
{
polar1[] x = new polar1[DSP1.Length];
for (int v = 0; v < N; v++)
{
x[v].real = DSP1[v];
x[v].img = 0;
}
F = FFT(x);
int temp;
}
public polar1[] FFT(polar1[] x)
{
int N2 = x.Length;
polar1[] X = new polar1[N2];
if (N2 == 1)
{
return x;
}
polar1[] odd = new polar1[N2 / 2];
polar1[] even = new polar1[N2 / 2];
polar1[] Y_Odd = new polar1[N2 / 2];
polar1[] Y_Even = new polar1[N2 / 2];
for (int t = 0; t < N2 / 2; t++)
{
even[t].img = x[t * 2].img;
even[t].real = x[t * 2].real;
odd[t].img = x[(t * 2) + 1].img;
odd[t].real = x[(t * 2) + 1].real;
}
Y_Even = FFT(even);
Y_Odd = FFT(odd);
polar1 temp4;
for (int k = 0; k < (N2 / 2); k++)
{
temp4 = Complex1(k, N2);
X[k].real = Y_Even[k].real + (Y_Odd[k].real * temp4.real);
X[k + (N2 / 2)].real = Y_Even[k].real - (Y_Odd[k].real * temp4.real);
X[k].img = Y_Even[k].img + (Y_Odd[k].real * temp4.img);
X[k + (N2 / 2)].img = Y_Even[k].img - (Y_Odd[k].real * temp4.img);
}
return X;
}
public double magnitude( polar1 temp)
{
double tempD;
tempD = Math.Sqrt ( (temp.img * temp.img) + (temp.real * temp.real));
return tempD;
}
public polar1 Complex2(int K, int N, int F3)
{
polar1 temp;
double temp1;
temp1 = (2D * K *F3) / N;
if (temp1 % 2 == 0 || temp1 == 0)
{
temp.real = 1D;
temp.img = 0D;
}
else if ((temp1 - 1) % 2 == 0)
{
temp.real = -1D;
temp.img = 0D;
}
else if ((temp1 / .5D) - 1 % 2 == 0)
{
if ((temp1 - .5D) % 2 == 0)
{
temp.real = 0D;
temp.img = -1D;
}
else
{
temp.real = 0D;
temp.img = 1D;
}
}
else
{
temp.real = Math.Cos(temp1 * Math.PI);
temp.img = -1D * Math.Sin(temp1 * Math.PI);
}
return temp;
}
public polar1 Complex1(int K, int N3)
{
polar1 temp;
double temp1;
temp1 = (2D * Math.PI *K) / N3;
temp.real = Math.Cos(temp1);
temp.img = Math.Sin(temp1);
return temp;
}
public int Apm(double[] img, double[] real)
{
for (int i = 0; i < R; i++)
{
img[i] = F[i].img;
real[i] = F[i].real;
}
return R;
}
public int frequencies(float [] freq, float [] Ctemp)
{
bool flag = false;
bool flagD = false;
float tempOld = 0;
float tempNew =0;
int tempc = 0;
int counter = 0;
for (int i = 0; i < R; i++)
{
if (((i / N) * Fs) >= (Fs / 2))
{
return counter;
}
if ((int)F[i].img != 0 )
{
flag = true;
tempOld = (float)(Math.Abs(F[i].img));
}
else
{
if (flagD == true)
{
freq[counter] = ((float)tempc / (float)N) * Fs;
Ctemp[counter] = tempNew; //magnitude(F[tempc]);
counter++;
flagD = false;
}
flag = false;
tempOld = 0;
tempNew = 0;
}
if(flag == true)
{
if (tempOld > tempNew)
{
tempNew = tempOld;
tempc = i;
flagD = true;
}
}
}
return counter;
}
}