**Introduction**

1. It is an interactive, graphics-based program that allows you to solve problems by creating models using a set of built-in “blocks.”

2. It is part of the MATLAB software suite, and requires MATLAB to run.

**Applications**

1. Designed to provide a convenient method for analyzing dynamic systems, i.e., systems that change with time.

2. It found early acceptance in the signal processing community, and is reminiscent of the approach used to program analog computers .

3. One way to think of Simulink is as a virtual analog computer.

4. Its strength is its ability to model dynamic systems—which are modelled mathematically as differential equations.

**Getting Started**

To start Simulink, open MATLAB and type simulink into the command window or select the Simulink icon from the Shortcut toolbar.

The Simulink Library Browser opens, showing the available libraries of blocks used to create a Simulink model.

To view the blocks, either select the library from the left-hand pane or double click on the icons in the right-hand pane.

To create a new model, select File ➞ New ➞ Model from the browser window.

**Model 1**

First model will simply add two numbers.

From the library, click and drag the constant block into the model window.

Repeat the process, so that there are two copies of constant block in the model.

Now drag the sum block into the model.

Draw connections between the constants and sum block by clicking and dragging between the ports.

To add a display, select and drag display block to model and connect it to output port of sum block.

The last thing we need to do before running the model is to adjust the simulation time, from the box on the menu bar.

Run the simulation by selecting the run button on the toolbar or by selecting Simulation ➞ Start from the menu bar.

Save this model in the usual way, by selecting File ➞ Save and adding an appropriate name.

The files are stored with the extension, .mdl.

**Model 2**

To solve differential equations with Simulink, create a model by dragging the appropriate blocks onto the model window, and connect them.

The blocks include; a clock, to generate times (Source library), a math function block, modified in the parameter window to square the block input (Math Operations library), a sum block (Commonly Used Blocks library), an integrator block (Continuous library), and a scope block (Sink library).

Connect all the blocks as shown in figure and the desired result is displayed.