# Challenges ## 1 Getting Started ### 1.1 Using MATLAB as a Calculator Use the MATLAB command prompt to perform the following operations: * [ ] 15 - 21 * [ ] 42 x 6 * [ ] 7 ÷ 2 * [ ] 8 ÷ 2(2 + 2) {% hint style="success" %} Answer the following questions: * [ ] What happens in the Workspace each time you enter a new command? * [ ] How can you 'recall' a previous command if you want to edit it? * [ ] Which order of operations does MATLAB use: BODMAS (Brackets, Order, Division, Multiplication, Addition, Subtraction) or PEMDAS (Parentheses, Exponents, Multiplication, Division, Addition, Subtraction)? {% endhint %} ### 1.2 Saving your work * [ ] Create a folder called "Workshop" and set it as the current working directory. * [ ] Inside your new folder, create a script called "workshop\_script". You can use this script to take notes and work through the rest of the challenges. {% hint style="info" %} Hint: for information on Live scripts, visit {% endhint %} ## 2 Variables ### 2.1 The magic number * [ ] Assign any integer number value to a variable called `x` * [ ] Create a new variable `y` which is the sum of `x` and the number one larger than `x` * [ ] Now create `z` starting with `y` add 9 and divide by 2. * [ ] Then subtract `x` and multiply by 20. * [ ] What did you get as the final value of `z`? ### 2.2 The Workspace * [ ] Save your Workspace: `save filename.mat`, where `filename` is any name you choose. * [ ] Clear your Workspace: `clear` * [ ] Load a previous Workspace: `load filename.mat` {% hint style="info" %} Hint: To save only one variable, `x`, use: `>> save filename.mat x`\ and to clear only one variable, `x`, use: `>> clear x` When you load a Workspace, this won't clear existing variables in your Workspace; it will add to your existing Workspace. {% endhint %} ### 2.3 Extension: What's in a name * [ ] Enter your name as a string: `name1`. * [ ] Create another variable, `name2`, and enter someone else's name. * [ ] Try adding the strings together like we did with numbers earlier. What happens? ## 3 Vectors and matrices ### 3.1 Vectors and matrices * [ ] Define the matrix `M` and row vector `p` shown below:![](https://firebasestorage.googleapis.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MfG9RzQCZQ-JfoVLlzk%2Fuploads%2Fz4oH5tZB8KZlagahr4Pq%2Ffile.png?alt=media) * [ ] Create a *column* vector called `ages` which contains the ages of three people: `age1`, `age2` and `age3`. * [ ] What is the size of each of these arrays? {% hint style="info" %} Hint: You can check the size of a variable `x`, on MATLAB using the function `size(x)` {% endhint %} ### 3.2 Random arrays * [ ] Create a row vector which starts at 7 and ends at 19, counting up by 3. * [ ] Create a row vector which starts at 10 and ends at 0, counting *down* by 2. * [ ] Create a column vector of five 1s. * [ ] Create a size 3x3 matrix array of random numbers. {% hint style="info" %} Hint: To get random numbers in MATLAB you will need to use the `rand()` function. Use 'Search Documentation' in the top right corner to learn about`rand` {% endhint %} ### 3.3 Indexing * [ ] Define the matrix `M` and row vector `p` shown below:![](https://firebasestorage.googleapis.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MfG9RzQCZQ-JfoVLlzk%2Fuploads%2Ffo5XjkZMEDGzPUHBbTxb%2Ffile.png?alt=media) * [ ] Extract the second column of `M` as a column vector called `col2`. * [ ] Using indexing on `p`, let `q` be another row vector with the elements of `p` in reverse (that is, you should get `q = [2 14 5 9 2 17]`). * [ ] Use assignment (`=`) to edit `p` to replace the second and last elements with 3 (you should get: `[17 3 9 5 14 3]`). * [ ] Use the keyword `end` to get the *second-last* element of `p`. ## 4 Array Operations ### 4.1 Operation matrix * [ ] The following array contains the average highest (column 1) and average lowest (column 2) temperatures (°F) in Los Angeles for each month in the calendar year: \ `F = [67, 51; 67, 51; 67, 51; 69, 53; 70, 56; 73, 58;`\ `77, 62; 79, 62; 78, 62; 75, 59; 71, 55; 67, 51]`.\ Convert these temperatures to °C using this formula: °C = (°F - 32) x 5 / 9 * [ ] Define the column vector `a = [3; 1; 2]` and the matrix `A = [6, 2, 6; 10, 4, 8]`. \ Multiply both of these arrays together, noting that there is only one way to do this. What is the size of the result? {% hint style="info" %} Hint: Recall you can check the size of a variable using the function `size()` {% endhint %} ### 4.2 Extension * [ ] Transpose the vector `a = [3; 1; 2]` from the previous challenge to create `a_transpose`. Now try again to multiply the result with `A` * [ ] Find the determinant and inverse of `G = [1, 3; 4, -1]`. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://meirian.gitbook.io/matlab/getting-started/challenges.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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