How about x = 1 - x?
Or if you want it to be time based use Timer % 2
Oh, you wanted the values between 0 and 1 as well.
how about Math.Abs(100 - (Timer % 200)) / 100
Where timer is something like DateTime.Now.TimeOfDay.TotalMilliseconds
Edit:
My tests indicate that this is more than twice as fast as the Sin method. For 1 million iterations, the sin method takes .048 seconds while the Abs method takes about .023 seconds. Also, you get different waveforms out of the two, of course. Sin produces a Sine wave, while Abs produces a triangular wave.
static void Main(string[] args)
{
System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
sw.Start();
const int count = 1000000;
float[] results = new float[count];
for (int i = 0; i < count; i++)
{
results[i] = AbsPulse(i/1000000F);
//results[i] = SinPulse(i / 1000000F);
}
sw.Stop();
Console.WriteLine("Time Elapsed: {0} seconds", sw.Elapsed.TotalSeconds);
char[,] graph = new char[80, 20];
for (int y = 0; y <= graph.GetUpperBound(1); y++)
for (int x = 0; x <= graph.GetUpperBound(0); x++)
graph[x, y] = ' ';
for (int x = 0; x < count; x++)
{
int col = x * 80 / count;
graph[col, (int)(results[x] * graph.GetUpperBound(1))] = 'o';
}
for (int y = 0; y <= graph.GetUpperBound(1); y++)
{
for (int x = 0; x < graph.GetUpperBound(0); x++)
Console.Write(graph[x, y]);
Console.WriteLine();
}
}
static float AbsPulse(float time)
{
const int frequency = 10; // Frequency in Hz
const int resolution = 1000; // How many steps are there between 0 and 1
return Math.Abs(resolution - ((int)(time * frequency * 2 * resolution) % (resolution * 2))) / (float)resolution;
}
static float SinPulse(float time)
{
const float pi = 3.14F;
const float frequency = 10; // Frequency in Hz
return 0.5F * (1 + (float)Math.Sin(2 * pi * frequency * time));
}