public static void EstimatePi(Context ctx, int batchs, ulong batchSize, double error)
{
const ulong seed = 0UL;
// allocate buffer for the generated points and a scalar to hold the simulated value of pi
var points = ctx.Device.Allocate <double2>(Shape.Create((long)batchSize));
var pi = ctx.Device.Allocate <double>(Shape.Scalar);
// transform that checks if point is inside unit square or not
// the value 4.0 is because we only simulate points in positive quadrant
var pis = Map(points, point => (point.x * point.x + point.y * point.y) < 1.0 ? 4.0 : 0.0);
// iterate over multiple batches
for (var i = 0; i < batchs; ++i)
{
Console.WriteLine($"Batch {i}");
// generates random numbers, apply the mapping followed by a mean reduction
var offset = batchSize * (ulong)i;
ctx.Assign(points, RandomUniform <double2>(seed: seed, offset: offset));
ctx.Assign(pi, i == 0 ? ReduceMean(pis) : (pi + ReduceMean(pis)) / 2.0);
}
Console.WriteLine($"Pi = {pi.ToScalar()}");
Assert.That(pi.ToScalar(), Is.EqualTo(Math.PI).Within(error));
}
public static Tensor <T> Eval <T>(this Context context, Expr <T> expr)
{
var tensor = context.Device.Allocate <T>(expr.Shape);
context.Assign(tensor, expr);
return(tensor);
}
public static Tensor <T> Allocate <T>(this Context context, Shape shape, T initValue)
{
var tensor = context.Device.Allocate <T>(shape);
context.Assign(tensor, initValue.AsScalar());
return(tensor);
}
public static void ReferenceThenCopyThenAssignGpu()
{
const int n = 1000;
var arrayA = GenerateRandomDoubleData(n, 1, 100);
var arrayB = new double[n];
var cpuA = arrayA.AsTensor();
var cpuB = arrayB.AsTensor();
var gpuA = gpu.Device.Allocate <double>(Shape.Create(n));
var gpuB = gpu.Device.Allocate <double>(Shape.Create(n));
gpu.Copy(gpuA, cpuA);
gpu.Assign(gpuB, gpuA);
// this copy need to sync, since cpuB is just a reference
gpu.Copy(cpuB, gpuB).Wait();
gpuB.Print();
Assert.IsTrue(arrayB.SequenceEqual(arrayA));
}
public static Task Assign <T>(this Context context, Tensor <T> tensor, T scalar)
{
return(context.Assign(tensor, scalar.AsScalar()));
}
