Math blocks (Sum, Gain, Product) in Simulink - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add two input signals using the Sum block.

Simulink

sum_block = Simulink.BlockDiagram.createSubsystem('Sum');
sum_block.BlockType = '[1]';

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

ASum

BGain

CProduct

DConstant

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Gain' instead of 'Sum' block type.

Confusing 'Product' block with 'Sum' block.

The Sum block adds input signals together. Setting BlockType to 'Sum' creates this block.

2fill in blank

medium

Complete the code to set the Gain block's gain value to 5.

Simulink

gain_block = Simulink.BlockDiagram.createSubsystem('Gain');
gain_block.BlockType = 'Gain';
gain_block.Gain = '[1]';

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

A10

B5

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Setting Gain to 1 (no change).

Using string instead of numeric value.

The Gain block multiplies input by the gain value. Setting Gain to '5' multiplies input by 5.

3fill in blank

hard

Fix the error in the Product block configuration to multiply three inputs.

Simulink

product_block = Simulink.BlockDiagram.createSubsystem('Product');
product_block.BlockType = 'Product';
product_block.NumberOfInputs = [1];

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

A4

B2

C1

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Leaving NumberOfInputs at default 2 when three inputs are connected.

Setting NumberOfInputs to 1, which disables multiplication.

To multiply three inputs, NumberOfInputs must be set to 3.

4fill in blank

hard

Fill in the blank to create a Sum block that subtracts the second input from the first.

Simulink

sum_block = Simulink.BlockDiagram.createSubsystem('Sum');
sum_block.BlockType = 'Sum';
sum_block.Inputs = '[1]';

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

A'--'

B'++'

C'+-'

D'-+'

Attempts:

3 left

💡 Hint

Common Mistakes

Using '++' which adds both inputs.

Using '--' which subtracts both inputs.

The Inputs property uses signs to define addition or subtraction for each input. '+-' means add first input, subtract second.

5fill in blank

hard

Fill all three blanks to create a Gain block with gain 3 and a Product block to multiply three inputs.

Simulink

gain_block = Simulink.BlockDiagram.createSubsystem('Gain');
gain_block.BlockType = '[1]';
gain_block.Gain = [2];
product_block = Simulink.BlockDiagram.createSubsystem('Product');
product_block.BlockType = 'Product';
product_block.NumberOfInputs = [3];

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

ASum

B3

DGain

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up block types.

Using string instead of number for gain or NumberOfInputs.

Set gain_block BlockType to 'Gain', Gain to 3, and product_block NumberOfInputs to 3 to multiply three inputs.

Practice

1.

What does the Sum block do in Simulink?

easy

A. Divides one input by another

B. Multiplies input by a constant

C. Adds or subtracts multiple inputs

D. Calculates the average of inputs

Solution

1. Step 1: Understand the Sum block function

   The Sum block in Simulink is designed to add or subtract multiple input signals.

2. Step 2: Compare with other blocks

   Gain multiplies by a constant, Product multiplies inputs, so Sum is for addition/subtraction.

3. Final Answer:

   Adds or subtracts multiple inputs -> Option C

4. Quick Check:

   Sum block = Adds or subtracts [OK]

Hint: Sum block adds or subtracts inputs, not multiply [OK]

Common Mistakes:

• Confusing Sum with Product block
• Thinking Sum multiplies inputs
• Mixing Gain and Sum functions

2.

Which of the following is the correct way to set a Gain block to multiply input by 5 in Simulink?

Gain = ?

easy

A. Gain = 5

B. Gain = 1/5

C. Gain = 0

D. Gain = -5

Solution

1. Step 1: Understand Gain block parameter

   The Gain block multiplies the input by the value set in its Gain parameter.

2. Step 2: Set Gain to multiply by 5

   To multiply input by 5, set Gain = 5 (not fraction or zero).

3. Final Answer:

   Gain = 5 -> Option A

4. Quick Check:

   Gain block multiplies input by Gain value [OK]

Hint: Gain value is the multiplier number directly [OK]

Common Mistakes:

• Using reciprocal instead of multiplier
• Setting Gain to zero
• Using negative value when positive needed

3.

Given two input signals to a Product block: 3 and 4, what is the output?

Output = Product(3, 4)

medium

A. 12

B. 7

C. 1.33

D. 0

Solution

1. Step 1: Understand Product block operation

   The Product block multiplies all its input signals together.

2. Step 2: Multiply inputs 3 and 4

   3 multiplied by 4 equals 12.

3. Final Answer:

   12 -> Option A

4. Quick Check:

   3 * 4 = 12 [OK]

Hint: Product block multiplies all inputs together [OK]

Common Mistakes:

• Adding inputs instead of multiplying
• Dividing inputs
• Confusing Product with Sum block

4.

Identify the error in this Sum block configuration: List of signs = '+-' with two inputs 5 and 3.

What is the output?

medium

A. 8

B. 2

C. -8

D. Error due to invalid signs

Solution

1. Step 1: Interpret Sum block signs

   Signs '+-' mean first input is added, second input is subtracted.

2. Step 2: Calculate output with inputs 5 and 3

   Output = 5 + (-3) = 2.

3. Final Answer:

   2 -> Option B

4. Quick Check:

   5 - 3 = 2 [OK]

Hint: Signs '+-' mean add first, subtract second input [OK]

Common Mistakes:

• Adding both inputs ignoring signs
• Using wrong sign order
• Expecting error for valid signs

5.

You have three inputs: 2, 3, and 4. You want to first multiply 2 and 3, then multiply the result by 4 using Simulink blocks. Which combination of blocks achieves this?

Options:
A) Product block with inputs 2, 3, 4
B) Product block with inputs 2 and 3, then Gain block with gain 4 on output
C) Sum block with inputs 2, 3, 4 and Gain block with gain 4
D) Gain block with gain 2, then Product block with inputs 3 and 4

hard

A. Product block with inputs 2, 3, 4

B. Gain block with gain 2, then Product block with inputs 3 and 4

C. Sum block with inputs 2, 3, 4 and Gain block with gain 4

D. Product block with inputs 2 and 3, then Gain block with gain 4 on output

Solution

1. Step 1: Multiply 2 and 3 first

   Use a Product block with inputs 2 and 3 to get 6.

2. Step 2: Multiply result by 4

   Use a Gain block with gain 4 on the output of the first Product block to multiply 6 by 4.

3. Step 3: Check other options

   Product block with inputs 2, 3, 4 multiplies all three at once (correct mathematically but not stepwise). Sum block with inputs 2, 3, 4 and Gain block with gain 4 uses Sum incorrectly. Gain block with gain 2, then Product block with inputs 3 and 4 multiplies 3 and 4 first, not 2 and 3.

4. Final Answer:

   Product block with inputs 2 and 3, then Gain block with gain 4 on output -> Option D

5. Quick Check:

   Stepwise multiply = Product then Gain [OK]

Hint: Use Product first, then Gain for stepwise multiplication [OK]

Common Mistakes:

• Multiplying all inputs at once ignoring steps
• Using Sum block for multiplication
• Wrong order of operations