# NAG CPP Interfaceopt::CommE04WB::setter_centraldiff-interval

## 1Description

If the algorithm switches to central differences because the forward-difference approximation is not sufficiently accurate, the value of $r$ is used as the difference interval for every element of $x$
Used by: centraldiff-interval in e04ucf and e04uff (no CPP interface).
CommE04WB::setter_centraldiff-interval returns a reference to the communication class itself.

## 2Specification

 CommE04WB& CentralDifferenceInterval(double value = Default values are computed )
 CommE04WB& CentralDifferenceInterval(double value = Default values are computed , OptionalE04UE opt)

## 3Arguments

1: $\mathbf{value}$ double Scalar
On entry: the required value of the argument.
Default:
Default values are computed
2: $\mathbf{opt}$ OptionalE04UE Scalar
Optional argument container, derived from Optional.