/// <summary>
/// A random <see cref="double"/> between <paramref name="minValue"/> (inclusive) and <paramref name="maxValue"/>
/// (inclusive). If you wish to have an exclusive range,
/// use <see cref="MathExtensions.NextAfter(float, double)"/> to adjust the range.
/// <para/>
/// The code was inspired by GeoTestUtil from Apache Lucene.
/// </summary>
/// <param name="random">The <see cref="Random"/> instance.</param>
/// <param name="minValue">Left range boundary, inclusive. May be <see cref="double.NegativeInfinity"/>, but not <see cref="double.NaN"/>.</param>
/// <param name="maxValue">Right range boundary, inclusive. May be <see cref="double.PositiveInfinity"/>, but not <see cref="double.NaN"/>.</param>
/// <returns>A random <see cref="double"/> between <paramref name="minValue"/> (inclusive) and <paramref name="maxValue"/>
/// (inclusive).</returns>
/// <exception cref="ArgumentException"><paramref name="minValue"/> is greater than <paramref name="maxValue"/>.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="minValue"/> or <paramref name="maxValue"/> is <see cref="double.NaN"/>.</exception>
/// <exception cref="ArgumentNullException"><paramref name="random"/> is <c>null</c>.</exception>
public static double RandomDoubleBetween(Random random, double minValue, double maxValue)
{
if (random is null)
{
throw new ArgumentNullException(nameof(random));
}
if (maxValue < minValue)
{
throw new ArgumentException($"{nameof(minValue)} must be greater than or equal to {nameof(maxValue)}: {minValue}, {maxValue}");
}
if (double.IsNaN(minValue))
{
throw new ArgumentOutOfRangeException(nameof(minValue), $"{nameof(minValue)} must not be {nameof(double.NaN)}");
}
if (double.IsNaN(maxValue))
{
throw new ArgumentOutOfRangeException(nameof(maxValue), $"{nameof(maxValue)} must not be {nameof(double.NaN)}");
}
bool hasZero = minValue <= 0 && maxValue >= 0;
int pick = random.Next(
EvilRangeLeft +
EvilRangeRight +
EvilVeryCloseRangeEnds +
(hasZero ? EvilZeroOrNear : 0) +
EvilSimpleProportion +
EvilRandomRepresentationBits);
// Exact range ends
pick -= EvilRangeLeft;
if (pick < 0 || minValue == maxValue)
{
return(minValue);
}
pick -= EvilRangeRight;
if (pick < 0)
{
return(maxValue);
}
// If we're dealing with infinities, adjust them to discrete values.
Debug.Assert(minValue != maxValue);
if (double.IsInfinity(minValue))
{
minValue = minValue.NextUp();
}
if (double.IsInfinity(maxValue))
{
maxValue = maxValue.NextAfter(double.NegativeInfinity);
}
// Numbers "very" close to range ends. "very" means a few floating point
// representation steps (ulps) away.
pick -= EvilVeryCloseRangeEnds;
if (pick < 0)
{
if (random.NextBoolean())
{
return(FuzzUp(random, minValue, maxValue));
}
else
{
return(FuzzDown(random, maxValue, minValue));
}
}
// Zero or near-zero values, if within the range.
if (hasZero)
{
pick -= EvilZeroOrNear;
if (pick < 0)
{
int v = random.Next(4);
if (v == 0)
{
return(0d);
}
else if (v == 1)
{
return(-0.0d);
}
else if (v == 2)
{
return(FuzzDown(random, 0d, minValue));
}
else if (v == 3)
{
return(FuzzUp(random, 0d, maxValue));
}
}
}
// Simple proportional selection.
pick -= EvilSimpleProportion;
if (pick < 0)
{
return(minValue + (maxValue - minValue) * random.NextDouble());
}
// Random representation space selection. This will be heavily biased
// and overselect from the set of tiny values, if they're allowed.
pick -= EvilRandomRepresentationBits;
if (pick < 0)
{
long from = ToSortable(minValue);
long to = ToSortable(maxValue);
return(FromSortable(RandomNumbers.RandomInt64Between(random, from, to)));
}
throw new Exception("Unreachable.");
}
public static long NextInt64(Random random, long minValue, long maxValue)
{
return(RandomInts.RandomInt64Between(random, minValue, maxValue)); // LUCENENET: Moved general random data generation to RandomizedTesting.Generators
}
/**
* A random long from <code>min</code> to <code>max</code> (inclusive).
*/
public static long RandomInt64Between(long min, long max)
{
return(RandomNumbers.RandomInt64Between(Random, min, max));
}
