/// <summary>
/// Entry point for the score calculation.
///
/// Given a set of information about the current node
/// the number of visits to be made to the subtree,
/// an array of visit counts is returned
/// indicating the number of visits that should be made to each child.
/// </summary>
/// <param name="dualSelectorMode"></param>
/// <param name="paramsSelect"></param>
/// <param name="selectorID"></param>
/// <param name="dynamicVLossBoost"></param>
/// <param name="parentIsRoot"></param>
/// <param name="parentN"></param>
/// <param name="parentNInFlight"></param>
/// <param name="qParent"></param>
/// <param name="parentSumPVisited"></param>
/// <param name="p"></param>
/// <param name="w"></param>
/// <param name="n"></param>
/// <param name="nInFlight"></param>
/// <param name="numChildren"></param>
/// <param name="numVisitsToCompute"></param>
/// <param name="outputScores"></param>
/// <param name="outputChildVisitCounts"></param>
public static void ScoreCalcMulti(bool dualSelectorMode, ParamsSelect paramsSelect,
int selectorID, float dynamicVLossBoost,
bool parentIsRoot, float parentN, float parentNInFlight,
float qParent, float parentSumPVisited,
Span <float> p, Span <float> w, Span <float> n, Span <float> nInFlight,
int numChildren, int numVisitsToCompute,
Span <float> outputScores, Span <short> outputChildVisitCounts)
{
// Saving output scores only makes sense when a single visit being computed
Debug.Assert(!(outputScores != default && numVisitsToCompute > 1));
Debug.Assert(p.Length == MAX_CHILDREN);
Debug.Assert(w.Length == MAX_CHILDREN);
Debug.Assert(n.Length == MAX_CHILDREN);
Debug.Assert(nInFlight.Length == MAX_CHILDREN);
Debug.Assert(numChildren <= MAX_CHILDREN);
Debug.Assert(outputScores == default || outputScores.Length >= numChildren);
Debug.Assert(outputChildVisitCounts.Length >= numChildren);
int numBlocks = (numChildren / 8) + ((numChildren % 8 == 0) ? 0 : 1);
float virtualLossMultiplier;
if (ParamsSelect.VLossRelative)
{
virtualLossMultiplier = (qParent + paramsSelect.VirtualLossDefaultRelative + dynamicVLossBoost);
}
else
{
virtualLossMultiplier = paramsSelect.VirtualLossDefaultAbsolute;
}
float cpuctValue = paramsSelect.CalcCPUCT(parentIsRoot, dualSelectorMode, selectorID, parentN);
// Compute qWhenNoChildren
float fpuValue = -paramsSelect.CalcFPUValue(parentIsRoot);
// TODO: to be more precise, parentSumPVisited should possibly be updated as we visit children
bool useFPUReduction = paramsSelect.GetFPUMode(parentIsRoot) == ParamsSelect.FPUType.Reduction;
float qWhenNoChildren = useFPUReduction ? (+qParent + fpuValue * MathF.Sqrt(parentSumPVisited)) : fpuValue;
if (parentIsRoot &&
parentN > paramsSelect.RootCPUCTExtraMultiplierDivisor &&
paramsSelect.RootCPUCTExtraMultiplierExponent != 0)
{
cpuctValue *= MathF.Pow(parentN / paramsSelect.RootCPUCTExtraMultiplierDivisor,
paramsSelect.RootCPUCTExtraMultiplierExponent);
}
Compute(parentN, parentNInFlight, p, w, n, nInFlight, numChildren, numVisitsToCompute, outputScores,
outputChildVisitCounts, numBlocks, virtualLossMultiplier,
parentIsRoot ? paramsSelect.UCTRootNumeratorExponent : paramsSelect.UCTNonRootNumeratorExponent,
cpuctValue, qWhenNoChildren,
parentIsRoot ? paramsSelect.UCTRootDenominatorExponent : paramsSelect.UCTNonRootDenominatorExponent);
}
