Practice in MATLAB

  • Practice problem 1: Edit buggy.m so that when it runs, it produces this output in the Command Window:
    >> buggy
    ans =
         3
    ans =
       120
    ans =
        15
    ans =
        57
    ans =
         2
    ans =
             3125 
    ans =
       Inf
    ans =
        3.1416
    ans =
      314.1593
    ans =
       3.1416e+03
    ans =
         0
    ans =
       71.3208
    Welcome to CS112
    The square root of 853 is
    ans = 
       29.2062
    >> 
    
  • Practice problem 2: Create a new file called product.m (make sure it is in your lab1 folder). In this file, display your name, and then the product of the numbers 1 through 10.
  • Practice problem 3: Create a new file called hello.m (in your lab1 folder). We're going to work with 3 different values (the italics are the English description of the values):
    • 2 (2 times the quantity Pi squared)
    • √2 (the square root of 2)
    • (0.000001234 + 5.67 × 10-3) × 0.4567 × 10-4 (some hairy number)

    Write hello.m so that it produces output exactly like this:

      >> hello
    This is the start of my program
    ans =
       19.7392
    The square root of 2 is
    ans =
        1.4142
    ans =
       2.5901e-07
    The square root of 1010101 is 
       1.005e+03
    This is the end of my program
    >> 
    
    Note that you can change the format of the numbers by using format long to produce this output:
    >> hello
    This is the start of my program
    ans =
      19.73920880217872
    The square root of 2 is
    ans =
       1.41421356237310
    ans =
         2.590052567800000e-07
    The square root of 1010101 is 
       1.005037810234023e+03 
    This is the end of my program
    
    **Challenge: Change the 'square root of 1010101' output in the box above (the 3rd to last line) so that the text and value are displayed on the same line like this:
     The square root of 1010101 is 1005.0378 
Notes:
  • Inserting disp statements in your code can help pinpoint the location of bugs in your scripts (you can always remove the excess disp statements after your code works perfectly).
  • clc clears the Command Window, which some people like when running their code
  • Fastest way to re-run a script? Double-click on the name of the script in the Command History window (if you like the mouse) or hit the "up-arrow" key (if you prefer the keyboard) to yank back the last command, and then hit return.
  • A semicolon ; suppresses output. Try adding semicolons at the end of a few lines in your hello.m. Run hello.m and note the difference in the Command Window. (Today we are not producing a lot of output, but in the future, the semicolon will come in handy).
  • Practice problem 4: Save the file byggy.m you worked with in Problem 1 as first.m. Run it to make sure it contains no errors. Update the top of the file comments.

    Then make the necessary changes to first.m so, when you run it, it produces this output: