This is a ‘type interface.’ See Type Interfaces for more info on what that is.

A ValueCalculator is responsible for calculating a particular value at a particular point. This might be, for example, calculating the value of a figure of merit at various point samples during a Metropolis-Hastings random walk.

The type represented by PointType depends on the use of the ValueCalculator, and is should be documented by whoever uses it. For example, a Tomographer::ValueHistogramMHRWStatsCollector will call the ValueCalculator using the PointType of the random walk (see MHWalker Interface).

A ValueCalculator must be copy-constructible, and different threads must be able to operate safely on different copies.

typedef .. ValueType: The type of the returned value.

ValueType getValue(PointType pt) const: Get the value corresponding to a particular point pt.