static void SamplesUnchecked(System.Random rnd, int[] values, double p)
{
if (p == 1.0)
{
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
values[i] = 1;
}
});
return;
}
var uniform = rnd.NextDoubles(values.Length);
double rp = 1.0 - p;
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
values[i] = (int)Math.Ceiling(Math.Log(1.0 - uniform[i], rp));
}
});
}
static void SamplesUnchecked(System.Random rnd, int[] values, double[] cdfUnnormalized)
{
// TODO : use binary search to speed up this procedure.
double[] uniform = rnd.NextDoubles(values.Length);
double w = cdfUnnormalized[cdfUnnormalized.Length - 1];
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
var u = uniform[i] * w;
var idx = 0;
if (u == 0.0d)
{
// skip zero-probability categories
while (0.0d == cdfUnnormalized[idx])
{
idx++;
}
}
while (u > cdfUnnormalized[idx])
{
idx++;
}
values[i] = idx;
}
});
}
internal static void SamplesUnchecked(System.Random rnd, double[] values, double mean, double stddev)
{
if (values.Length == 0)
{
return;
}
// Since we only accept points within the unit circle
// we need to generate roughly 4/pi=1.27 times the numbers needed.
int n = (int)Math.Ceiling(values.Length * 4 * Constants.InvPi);
if (n.IsOdd())
{
n++;
}
var uniform = rnd.NextDoubles(n);
// Polar transform
double x, y;
int index = 0;
for (int i = 0; i < uniform.Length && index < values.Length; i += 2)
{
if (!PolarTransform(uniform[i], uniform[i + 1], out x, out y))
{
continue;
}
values[index++] = mean + stddev * x;
if (index == values.Length)
{
return;
}
values[index++] = mean + stddev * y;
if (index == values.Length)
{
return;
}
}
// remaining, if any
while (index < values.Length)
{
if (!PolarTransform(rnd.NextDouble(), rnd.NextDouble(), out x, out y))
{
continue;
}
values[index++] = mean + stddev * x;
if (index == values.Length)
{
return;
}
values[index++] = mean + stddev * y;
if (index == values.Length)
{
return;
}
}
}
static void SamplesUnchecked(System.Random rnd, double[] values, double location, double scale)
{
rnd.NextDoubles(values);
for (int i = 0; i < values.Length; i++)
{
var u = values[i] - 0.5;
values[i] = location - (scale * Math.Sign(u) * Math.Log(1.0 - (2.0 * Math.Abs(u))));
}
}
public void TestDoubles()
{
var random1 = new System.Random(1);
var random2 = new System.Random(1);
Assert.Equal(
actual: random1.NextDoubles().Take(10).ToArray(),
expected: Enumerable.Range(0, 10).Select(_ => random2.NextDouble()).ToArray()
);
}
static void SamplesUnchecked(System.Random rnd, double[] values, double location, double scale)
{
rnd.NextDoubles(values);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
values[i] = location + scale * Math.Tan(Constants.Pi * (values[i] - 0.5));
}
});
}
static void SamplesUnchecked(System.Random rnd, double[] values, double scale)
{
rnd.NextDoubles(values);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
values[i] = scale * Math.Sqrt(-2.0 * Math.Log(values[i]));
}
});
}
static void SamplesUnchecked(System.Random rnd, double[] values, double location, double scale)
{
rnd.NextDoubles(values);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
var u = values[i] - 0.5;
values[i] = location - (scale * Math.Sign(u) * Math.Log(1.0 - (2.0 * Math.Abs(u))));
}
});
}
static void SamplesUnchecked(System.Random rnd, int[] values, double p)
{
var uniform = rnd.NextDoubles(values.Length);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
values[i] = uniform[i] < p ? 1 : 0;
}
});
}
internal static void SamplesUnchecked(System.Random rnd, double[] values, double scale, double shape, double truncation)
{
if (values.Length == 0)
{
return;
}
double[] uniforms = rnd.NextDoubles(values.Length);
for (var j = 0; j < values.Length; ++j)
{
values[j] = InvCDFUncheckedImpl(scale, shape, truncation, uniforms[j]);
}
}
internal static void SamplesUnchecked(System.Random rnd, double[] values, double lower, double upper)
{
rnd.NextDoubles(values);
var difference = upper - lower;
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
values[i] = lower + values[i] * difference;
}
});
}
static void SamplesUnchecked(System.Random rnd, double[] values, double scale, double shape)
{
var power = -1.0 / shape;
rnd.NextDoubles(values);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
values[i] = scale * Math.Pow(values[i], power);
}
});
}
static void SamplesUnchecked(System.Random rnd, double[] values, double shape, double scale)
{
var exponent = 1.0 / shape;
rnd.NextDoubles(values);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
values[i] = scale * Math.Pow(-Math.Log(values[i]), exponent);
}
});
}
internal static void SamplesUnchecked(System.Random rnd, double[] values, double mu, double lambda)
{
if (values.Length == 0)
{
return;
}
double[] v = new double[values.Length];
MathNet.Numerics.Distributions.Normal.Samples(rnd, v, 0, 1);
double[] test = rnd.NextDoubles(values.Length);
for (var j = 0; j < values.Length; ++j)
{
values[j] = InverseGaussianSampleImpl(mu, lambda, v[j], test[j]);
}
}
internal static void SamplesUnchecked(System.Random rnd, double[] values, double a, double c, double k)
{
if (values.Length == 0)
{
return;
}
var k_inv = 1 / k;
var c_inv = 1 / c;
double[] u = rnd.NextDoubles(values.Length);
for (var j = 0; j < values.Length; ++j)
{
values[j] = a * Math.Pow(Math.Pow(1 - u[j], -k_inv) - 1, c_inv);
}
}
static void SamplesUnchecked(System.Random rnd, double[] values, double lower, double upper, double mode)
{
double ml = mode - lower, ul = upper - lower, um = upper - mode;
double u = ml / ul, v = ul * ml, w = ul * um;
rnd.NextDoubles(values);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
values[i] = values[i] < u
? lower + Math.Sqrt(values[i] * v)
: upper - Math.Sqrt((1 - values[i]) * w);
}
});
}
static void SamplesUnchecked(System.Random rnd, double[] values, double rate)
{
rnd.NextDoubles(values);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
// this happens very rarely
var r = values[i];
while (r == 0.0)
{
r = rnd.NextDouble();
}
values[i] = -Math.Log(r) / rate;
}
});
}
static void SamplesUnchecked(System.Random rnd, int[] values, double p, int n)
{
var uniform = rnd.NextDoubles(values.Length*n);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
int k = i*n;
int sum = 0;
for (int j = 0; j < n; j++)
{
sum += uniform[k + j] < p ? 1 : 0;
}
values[i] = sum;
}
});
}
static void SamplesUnchecked(System.Random rnd, int[] values, double lambda, double nu, double z)
{
var uniform = rnd.NextDoubles(values.Length);
CommonParallel.For(0, values.Length, 4096, (a, b) =>
{
for (int i = a; i < b; i++)
{
var u = uniform[i];
var p = 1.0 / z;
var cdf = p;
var k = 0;
while (u > cdf)
{
k++;
p = p * lambda / Math.Pow(k, nu);
cdf += p;
}
values[i] = k;
}
});
}
