Signal routing in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to route the input signal to output1.

MATLAB

output1 = [1];

Drag options to blanks, or click blank then click option'

AoutputSignal

Binput

CsignalIn

DinputSignal

Attempts:

3 left

💡 Hint

Common Mistakes

Using an undefined variable like outputSignal.

Confusing input and output variable names.

The variable inputSignal holds the input data that should be routed to output1.

2fill in blank

medium

Complete the code to route the input signal to output2 after applying a gain of 2.

MATLAB

output2 = 2 * [1];

Drag options to blanks, or click blank then click option'

AinputSignal

Binput

CoutputSignal

DsignalIn

Attempts:

3 left

💡 Hint

Common Mistakes

Using output variables instead of input.

Forgetting to multiply by 2.

The input signal inputSignal is multiplied by 2 to apply gain before routing to output2.

3fill in blank

hard

Fix the error in routing the signal to output3 with an offset of 5.

MATLAB

output3 = [1] + 5;

Drag options to blanks, or click blank then click option'

AoutputSignal

BsignalOut

CinputSignal

Dinput

Attempts:

3 left

💡 Hint

Common Mistakes

Using output variables instead of input.

Using undefined variables.

The input signal inputSignal should be used before adding the offset.

4fill in blank

hard

Fill both blanks to route inputSignal to output4 with gain 3 and offset 1.

MATLAB

output4 = [1] * 3 + [2];

Drag options to blanks, or click blank then click option'

AinputSignal

BoutputSignal

C1

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using output variables in place of input.

Using wrong offset value.

The input signal is multiplied by 3 and then 1 is added as offset.

5fill in blank

hard

Fill all three blanks to route inputSignal to output5 with gain 4, offset 2, and then subtract 3.

MATLAB

output5 = ([1] * [2] + [3]) - 3;

Drag options to blanks, or click blank then click option'

AinputSignal

B4

C2

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up gain and offset values.

Using wrong variable names.

The input signal is multiplied by 4, then 2 is added, and finally 3 is subtracted.

Practice

1. What is the main purpose of signal routing in MATLAB programming?

easy

A. To send data to different parts of a program based on conditions

B. To create graphical user interfaces

C. To perform mathematical calculations only

D. To store data permanently on disk

Solution

1. Step 1: Understand signal routing concept

   Signal routing means directing data flow to different parts depending on conditions.

2. Step 2: Match purpose with options

   Only To send data to different parts of a program based on conditions describes sending data based on conditions, which is signal routing.

3. Final Answer:

   To send data to different parts of a program based on conditions -> Option A

4. Quick Check:

   Signal routing = conditional data flow [OK]

Hint: Signal routing controls data flow based on conditions [OK]

Common Mistakes:

• Confusing signal routing with data storage
• Thinking it only does calculations
• Mixing it up with GUI creation

2. Which of the following is the correct syntax to route a signal based on a condition in MATLAB?

easy

A. if signal > 0 {
output = signal;
} else {
output = 0;
}

B. if (signal > 0) then
output = signal
else
output = 0
end if

C. if signal > 0
output = signal;
else
output = 0;
end

D. if signal > 0:
output = signal
else:
output = 0

Solution

1. Step 1: Recall MATLAB if-else syntax

   MATLAB uses 'if condition', statements, 'else', statements, and 'end' to close.

2. Step 2: Compare options with MATLAB syntax

   if signal > 0 output = signal; else output = 0; end matches MATLAB syntax exactly; others use syntax from other languages.

3. Final Answer:

   if signal > 0 output = signal; else output = 0; end -> Option C

4. Quick Check:

   MATLAB if-else ends with 'end' [OK]

Hint: MATLAB if-else blocks end with 'end' keyword [OK]

Common Mistakes:

• Using 'then' keyword (not in MATLAB)
• Using braces {} instead of end
• Using colons like Python

3. What will be the output of this MATLAB code?

signal = -5;
if signal > 0
    routed = 1;
else
    routed = -1;
end
routed

medium

A. -1

B. 1

C. 0

D. Error

Solution

1. Step 1: Check the condition signal > 0

   signal is -5, which is not greater than 0, so condition is false.

2. Step 2: Follow else branch

   Since condition is false, routed is assigned -1.

3. Final Answer:

   -1 -> Option A

4. Quick Check:

   signal = -5 -> routed = -1 [OK]

Hint: Check condition truth to pick if or else branch [OK]

Common Mistakes:

• Assuming negative numbers satisfy > 0
• Confusing output variable name
• Expecting zero output

4. Identify the error in this MATLAB signal routing code:

signal = 10;
if signal > 5
    output = 1;
else
    output = 0;

medium

A. Variable 'output' is not defined

B. Missing 'end' to close the if statement

C. Incorrect comparison operator

D. Using semicolons incorrectly

Solution

1. Step 1: Check if statement structure

   MATLAB requires 'end' to close if blocks.

2. Step 2: Verify code completeness

   The code lacks 'end' after else block, causing syntax error.

3. Final Answer:

   Missing 'end' to close the if statement -> Option B

4. Quick Check:

   if blocks must end with 'end' [OK]

Hint: Always close if with 'end' in MATLAB [OK]

Common Mistakes:

• Forgetting 'end' after if-else
• Thinking semicolons end blocks
• Misusing comparison operators

5. You want to route a signal in MATLAB to three different outputs based on its value:
- If signal < 0, output = -1
- If signal == 0, output = 0
- If signal > 0, output = 1
Which code correctly implements this routing?

hard

A. if signal < 0
output = -1;
else if signal == 0
output = 0;
else
output = 1;
end

B. if signal <= 0
output = -1;
elseif signal == 0
output = 0;
else
output = 1;
end

C. if signal < 0
output = -1;
if signal == 0
output = 0;
else
output = 1;
end

D. if signal < 0
output = -1;
elseif signal == 0
output = 0;
else
output = 1;
end

Solution

1. Step 1: Understand routing conditions

   We need three cases: less than 0, equal to 0, greater than 0.

2. Step 2: Check code correctness

   if signal < 0 output = -1; elseif signal == 0 output = 0; else output = 1; end uses if, elseif, else correctly with proper conditions and 'end'.

3. Step 3: Identify errors in other options

   if signal <= 0 output = -1; elseif signal == 0 output = 0; else output = 1; end wrongly uses <= which overlaps conditions; C uses two separate ifs causing logic errors; D uses 'else if' which is invalid syntax in MATLAB.

4. Final Answer:

   if signal < 0 output = -1; elseif signal == 0 output = 0; else output = 1; end -> Option D

5. Quick Check:

   Use if-elseif-else for multiple conditions [OK]

Hint: Use if-elseif-else for multiple exclusive conditions [OK]

Common Mistakes:

• Using overlapping conditions like <= and ==
• Using nested if without else properly
• Writing 'else if' instead of 'elseif'