Creating sine or square wave in C#

int sampleRate = 8000;
short[] buffer = new short[8000];
double amplitude = 0.25 * short.MaxValue;
double frequency = 1000;
for (int n = 0; n < buffer.Length; n++)
{
    buffer[n] = (short)(amplitude * Math.Sin((2 * Math.PI * n * frequency) / sampleRate));
}

d= 40000; //fundamental freq of sine/sample rate

for (int n = 0; n < d; n++)
{
    buffer[n] = (short)(amplitude * Math.Sin((2 * Math.PI * n * ) / d);
}