Help system and documentation in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this MATLAB help command?

Consider the following MATLAB command typed in the Command Window:

help plot

What will MATLAB display?

MATLAB

help plot

A Displays the documentation text describing the 'plot' function usage and examples.

B Runs the 'plot' function with no arguments and shows a blank figure.

C Shows an error message: 'Undefined function or variable 'plot''.

D Opens the MATLAB Editor with the source code of 'plot'.

💡 Hint

The 'help' command shows text documentation for functions.

The 'help' command in MATLAB displays the help text for the specified function, explaining its usage and options.

❓ Predict Output

intermediate

What does this MATLAB command display?

What is the output of this command?

doc sin

Assume MATLAB is running with GUI.

MATLAB

doc sin

A Runs the sine function on an empty input and returns an empty array.

B Opens the MATLAB Help browser showing detailed documentation for the 'sin' function.

C Displays an error: 'doc is not recognized'.

D Prints the first 10 values of the sine function in the Command Window.

💡 Hint

The 'doc' command opens the full documentation in a separate window.

The 'doc' command opens the MATLAB Help browser with detailed documentation and examples for the specified function.

🧠 Conceptual

advanced

Which statement about MATLAB function documentation is true?

Select the correct statement about how MATLAB function documentation works.

A The 'doc' command only works for user-defined functions, not built-in ones.

B The 'help' command executes the function and shows its output as documentation.

C Documentation comments must be placed at the end of the function file to be recognized.

D The first contiguous comment block in a function file is shown by the 'help' command.

💡 Hint

Think about where comments go to be shown by 'help'.

MATLAB shows the first block of contiguous comments at the start of a function file as its help text.

❓ Predict Output

advanced

What error does this MATLAB command produce?

What error message will this command produce?

help nonExistingFunction

MATLAB

help nonExistingFunction

A No documentation found for 'nonExistingFunction'.

B Displays the help text for the closest matching function.

C Syntax error: missing semicolon.

D Undefined function or variable 'nonExistingFunction'.

💡 Hint

What happens if you ask help for a function that does not exist?

If no help text is found for the function, MATLAB shows a message like ''nonExistingFunction' not found.'

🚀 Application

expert

How many lines of help text will this function display?

Given this MATLAB function saved as 'myFunc.m':

function y = myFunc(x)
%MYFUNC Multiply input by 2
%   y = myFunc(x) returns x multiplied by 2.
%   This function doubles the input value.

 y = 2 * x;
end

What will be the number of lines displayed when running help myFunc?

MATLAB

function y = myFunc(x)
%MYFUNC Multiply input by 2
%   y = myFunc(x) returns x multiplied by 2.
%   This function doubles the input value.

y = 2 * x;
end

A 5 lines

B 4 lines

C 3 lines

D 2 lines

💡 Hint

Count the contiguous comment lines at the start of the file.

MATLAB 'help' shows the contiguous comment lines starting with '%' after the function definition line. Here, there are 3 such lines.

Practice

1. What does the help command do in MATLAB?

easy

A. Shows a short explanation of a function in the command window

B. Opens a detailed graphical documentation page

C. Runs the function with default parameters

D. Edits the function's source code

Solution

1. Step 1: Understand the purpose of help

   The help command is designed to show a brief explanation or summary of a MATLAB function directly in the command window.

2. Step 2: Compare with other options

   doc opens detailed documentation, running or editing functions is unrelated to help.

3. Final Answer:

   Shows a short explanation of a function in the command window -> Option A

4. Quick Check:

   help shows short explanation [OK]

Hint: Remember: help = quick info in command window [OK]

Common Mistakes:

• Confusing help with doc
• Thinking help runs the function
• Assuming help edits code

2. Which of the following is the correct way to open detailed documentation for the function plot?

easy

A. open plot

B. help plot

C. doc plot

D. run plot

Solution

1. Step 1: Identify the command for detailed documentation

   The doc command opens the detailed documentation page with examples and explanations.

2. Step 2: Check other options

   help shows short info, open and run are not used for documentation.

3. Final Answer:

   doc plot -> Option C

4. Quick Check:

   doc opens detailed docs [OK]

Hint: Use doc for detailed help with examples [OK]

Common Mistakes:

• Using help instead of doc for detailed info
• Trying to use open or run commands
• Forgetting to type the function name after doc

3. What will be the output of the command help sum in MATLAB?

medium

A. It will execute the sum function on the current workspace variables

B. It will display a brief description of the sum function in the command window

C. It will open the full documentation page for sum in a separate window

D. It will show an error because help cannot be used with sum

Solution

1. Step 1: Understand what help sum does

   The help command shows a short explanation of the specified function, here sum, in the command window.

2. Step 2: Eliminate incorrect options

   doc opens full docs, help does not execute functions or cause errors for built-in functions.

3. Final Answer:

   It will display a brief description of the sum function in the command window -> Option B

4. Quick Check:

   help shows brief info [OK]

Hint: help shows short info, doc shows full docs [OK]

Common Mistakes:

• Confusing help with doc
• Expecting help to run the function
• Thinking help causes errors for built-in functions

4. You typed helpplot in MATLAB but got an error. What is the likely problem?

medium

A. You forgot to put a space between help and the function name

B. The help command does not work for plotting functions

C. You need to use docplot instead

D. The function plot does not exist in MATLAB

Solution

1. Step 1: Analyze the command helpplot

   This is a single word, so MATLAB looks for a function named helpplot, which does not exist.

2. Step 2: Correct usage of help

   The correct syntax is help plot with a space to ask for help on the plot function.

3. Final Answer:

   You forgot to put a space between help and the function name -> Option A

4. Quick Check:

   Use space after help [OK]

Hint: Always put space between help and function name [OK]

Common Mistakes:

• Typing help and function name without space
• Assuming help doesn't work for plot
• Trying docplot instead of doc plot

5. You want to learn how to use the fft function with examples and detailed explanations. Which command should you use and why?

hard

A. Use edit fft to read the source code and understand usage

B. Use help fft because it shows detailed examples

C. Use run fft to execute the function and see results

D. Use doc fft because it opens full documentation with examples

Solution

1. Step 1: Identify the need for detailed explanations and examples

   Detailed explanations and examples are found in the full documentation, not in the short help text.

2. Step 2: Choose the correct command

   doc fft opens the full documentation page with examples, while help fft shows only brief info.

3. Step 3: Understand why other options are incorrect

   run fft executes the function, edit fft opens source code which may not be helpful for beginners.

4. Final Answer:

   Use doc fft because it opens full documentation with examples -> Option D

5. Quick Check:

   doc = detailed docs with examples [OK]

Hint: Use doc for full docs and examples, help for quick info [OK]

Common Mistakes:

• Using help expecting detailed examples
• Trying to run function to learn usage
• Editing source code instead of reading docs