Simulink Reference

Derivative

Output the time derivative of the input

Library

Continuous

Description

The Derivative block approximates the derivative of its input by computing

where u is the change in input value and t is the change in time since the previous simulation time step. The block accepts one input and generates one output. The value of the input signal before the start of the simulation is assumed to be zero. The initial output for the block is zero.

The accuracy of the results depends on the size of the time steps taken in the simulation. Smaller steps allow a smoother and more accurate output curve from this block. Unlike blocks that have continuous states, the solver does not take smaller steps when the input changes rapidly.

When the input is a discrete signal, the continuous derivative of the input is an impulse when the value of the input changes, otherwise it is 0. You can obtain the discrete derivative of a discrete signal using

and taking the z-transform

Using linmod to linearize a model that contains a Derivative block can be troublesome. For information about how to avoid the problem, see Linearizing Models in Using Simulink.

Data Type Support

A Derivative block accepts and outputs a real signal of type double.

Dialog Box

Characteristics

Direct Feedthrough	Yes
Sample Time	Continuous
Scalar Expansion	N/A
States	0
Dimensionalized	Yes
Zero Crossing	No

Demux

Digital Clock