MATLAB Basics 2 simple calculations and use

Transcription

1 1 MATLAB Basics 2 simple calculations and use Anthony Rossiter University of Sheffield For a neat organisation of all videos and resources

2 Introduction 1. Demonstrates how to use basic MATLAB functionality. 2. An understanding of this is a precursor to the more advanced uses needed for general engineering problem solving. 3. Focus here is on BODMAS types of operations; more advanced operations are in later resources. 4. MATLAB supports both symbolic algebra and number crunching and is far easier to use than a hand calculator. 2 We give a quick overview of MATLAB tools and usage and then do a live demonstration of all aspects covered at the end.

3 Basic algebra MATLAB will handle any basic BODMAS type of operation. Simply type the desired computation and the answer will appear. We will demonstrate live but also show some typical screen dumps here for convenience. 3

4 Using variables One advantage of MATLAB compared to a calculator is the ease with which computations can be allocated to variables and therefore the answers stored for Variables later use. automatically stored in workspace for reuse. A simple illustration is given here. Use name= to allocate to a variable name. 4

5 Mathematical functions 5 Most simple functions can be obtained by typing the names, e.g. If the computation is not allocated to a variable, MATLAB stores in the variable ans. For more functions, type >> help elfun

6 It is easy to write long expressions as may arise in problem solving. These are far easier to view than on a typical calculator. If you make a mistake, use uparrow to recall the command and simply edit as required. Long expressions Changed here only 6

7 Rather than typing into the command window over and over again, it is better to save the core commands in a file. MATLAB provides script files for this. Select new script and save in a folder of your choice. Being efficient Select here. 7

8 8 Select here to give the file a name and select a folder to save to. Default ending for MATLAB files is.m Do not change this! We will demonstrate the process at the end of this video. Script files covered slowly in resource 4.

9 Opening a saved file Go to the file tab and open from there. Advisable to do this way and do not find the file on windows explorer and open from there. Opening from within MATLAB ensures that some core software links work effectively. 9 ALWAYS open files using this tab! (or open from within the file editor window)

10 Algebra 10 MATLAB will also do symbolic algebra. To do this, variables must be defined as symbolic the default is variables contain a numeric value. Note different variable types.

11 Evaluating symbolic expressions 11 A file called subs.m will substitute numerical values into symbolic expressions. This is easiest understood by a demonstration. Create symbolic variable. m( f ) f m(4) f Expression and value go here. Symbolic variables covered slowly in resource 7.

12 12 LIVE DEMONSTRATIONS WITH MATLAB Open the following and try the instructions matlab_basics2.m matlab_basics2b.m

13 Conclusions 13 Demonstrated the effectiveness of MATLAB for carrying out and saving simple algebra and numerical computations. 1. Allows transparency for very long expressions. 2. Allows easy recall of commands for editing. 3. Allows easy definition and saving of variables to memory (denoted the workspace). I prefer to save regular and validated complicated expressions or sequences of calculations into a script file for re-use whenever I need them.

14 For a neat organisation of all videos and resources Anthony Rossiter Department of Automatic Control and Systems Engineering University of Sheffield University of Sheffield This work is licensed under the Creative Commons Attribution 2.0 UK: England & Wales Licence. To view a copy of this licence, visit or send a letter to: Creative Commons, 171 Second Street, Suite 300, San Francisco, California 94105, USA. It should be noted that some of the materials contained within this resource are subject to third party rights and any copyright notices must remain with these materials in the event of reuse or repurposing. If there are third party images within the resource please do not remove or alter any of the copyright notices or website details shown below the image. (Please list details of the third party rights contained within this work. If you include your institutions logo on the cover please include reference to the fact that it is a trade mark and all copyright in that image is reserved.)