# Documentation

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## Programming and Scripts

The simplest type of MATLAB® program is called a script. A script is a file with a `.m` extension that contains multiple sequential lines of MATLAB commands and function calls. You can run a script by typing its name at the command line.

### Sample Script

To create a script, use the `edit` command,

`edit plotrand`

This opens a blank file named `plotrand.m`. Enter some code that plots a vector of random data:

```n = 50; r = rand(n,1); plot(r)```

Next, add code that draws a horizontal line on the plot at the mean:

```m = mean(r); hold on plot([0,n],[m,m]) hold off title('Mean of Random Uniform Data')```

Whenever you write code, it is a good practice to add comments that describe the code. Comments allow others to understand your code, and can refresh your memory when you return to it later. Add comments using the percent (`%`) symbol.

```% Generate random data from a uniform distribution % and calculate the mean. Plot the data and the mean. n = 50; % 50 data points r = rand(n,1); plot(r) % Draw a line from (0,m) to (n,m) m = mean(r); hold on plot([0,n],[m,m]) hold off title('Mean of Random Uniform Data')```

Save the file in the current folder. To run the script, type its name at the command line:

`plotrand`

You can also run scripts from the Editor by pressing the Run button, .

### Loops and Conditional Statements

Within a script, you can loop over sections of code and conditionally execute sections using the keywords `for`, `while`, `if`, and `switch`.

For example, create a script named `calcmean.m` that uses a `for` loop to calculate the mean of five random samples and the overall mean.

```nsamples = 5; npoints = 50; for k = 1:nsamples currentData = rand(npoints,1); sampleMean(k) = mean(currentData); end overallMean = mean(sampleMean)```

Now, modify the `for` loop so that you can view the results at each iteration. Display text in the Command Window that includes the current iteration number, and remove the semicolon from the assignment to `sampleMean`.

```for k = 1:nsamples iterationString = ['Iteration #',int2str(k)]; disp(iterationString) currentData = rand(npoints,1); sampleMean(k) = mean(currentData) end overallMean = mean(sampleMean)```

When you run the script, it displays the intermediate results, and then calculates the overall mean.

`calcmean`
```Iteration #1 sampleMean = 0.3988 Iteration #2 sampleMean = 0.3988 0.4950 Iteration #3 sampleMean = 0.3988 0.4950 0.5365 Iteration #4 sampleMean = 0.3988 0.4950 0.5365 0.4870 Iteration #5 sampleMean = 0.3988 0.4950 0.5365 0.4870 0.5501 overallMean = 0.4935```

In the Editor, add conditional statements to the end of `calcmean.m` that display a different message depending on the value of `overallMean`.

```if overallMean < .49 disp('Mean is less than expected') elseif overallMean > .51 disp('Mean is greater than expected') else disp('Mean is within the expected range') end```

Run `calcmean` and verify that the correct message displays for the calculated `overallMean`. For example:

```overallMean = 0.5178 Mean is greater than expected```

### Script Locations

MATLAB looks for scripts and other files in certain places. To run a script, the file must be in the current folder or in a folder on the search path.

By default, the `MATLAB` folder that the MATLAB Installer creates is on the search path. If you want to store and run programs in another folder, add it to the search path. Select the folder in the Current Folder browser, right-click, and then select Add to Path.