To switch the display of the derivative on or off then select the Derivative check box on the View window.
Three methods are available for calculating the derivative either: User-Defined Function and the central difference method cannot be used if there is an irregular sampling interval. If there are undefined function values then only the exact derivative can be calculated, at the points where the function is defined.
The derivative is calculated at the current Sampling Interval and displayed over the currently defined Settings limits. Sample points are joined by straight line segments, where possible, to give the appearance of a continuous function. If there are undefined Undefined Values for the derivative then these will not be represented on the graph.