Abstract class for all numerical integration methods (1D and multi-dim) Interface defining the common methods for the numerical integrator classes of one and multi dimensions The derived class VirtualIntegratorOneDim defines the methods for one-dimensional integration. The derived class VirtualIntegratorMultiDim defines the method for multi-dimensional integration. The concrete classes for one dimension (e.g. GSLIntegrator) or multi-dimension (e.g. GSLMCIntegrator) can be created using the plug-in manager. Users should not use directly this class but the concrete classes ROOT::Math::IntegratorOneDim or ROOT::Math::IntegratorMultiDim @ingroup Integration
set the options (should be re-implemented by derived classes -if more options than tolerance exist