Numeric types (double, single, integer) in MATLAB - Mini Project: Build & Apply

Working with Numeric Types in MATLAB

📖 Scenario: You are working on a simple calculator program that needs to handle numbers in different formats. Understanding how to create and use different numeric types like double, single, and integer is important for saving memory and ensuring correct calculations.

🎯 Goal: Learn how to create variables with numeric types double, single, and int32 in MATLAB, and see how they behave when printed.

📋 What You'll Learn

Create variables with numeric types double, single, and int32

Assign specific values to each variable

Display the values and their types

💡 Why This Matters

🌍 Real World

Numeric types are important in engineering and scientific computing where memory and precision matter.

💼 Career

Understanding numeric types helps in optimizing MATLAB code for performance and accuracy in data analysis and simulations.

1

Create a double variable

Create a variable called numDouble and assign it the value 10.5 as a double type.

MATLAB

% Create a variable called numDouble with value 10.5 as double
% Your code here

Hint

In MATLAB, numbers are double by default. Just assign the value directly.

2

Create a single variable

Create a variable called numSingle and assign it the value 10.5 as a single type using the single() function.

MATLAB

numDouble = 10.5;
% Create a variable called numSingle with value 10.5 as single
% Your code here

Hint

Use the single() function to convert a number to single precision.

3

Create an int32 variable

Create a variable called numInt and assign it the integer value 10 as an int32 type using the int32() function.

MATLAB

numDouble = 10.5;
numSingle = single(10.5);
% Create a variable called numInt with value 10 as int32
% Your code here

Hint

Use the int32() function to create a 32-bit integer variable.

4

Display the values and their types

Use disp() to print the values of numDouble, numSingle, and numInt. Then use class() inside disp() to print their types.

MATLAB

numDouble = 10.5;
numSingle = single(10.5);
numInt = int32(10);
format short g;
% Display the values and their types below
% Your code here

Hint

Use disp(variable) to show the value and disp(class(variable)) to show the type.

Practice

1. Which numeric type is the default in MATLAB when you create a number like 5 without specifying its type?

easy

A. single

B. uint8

C. int32

D. double

Solution

1. Step 1: Understand MATLAB default numeric type

   By default, MATLAB stores numbers as double precision floating-point values.

2. Step 2: Check the given number type

   The number 5 without any type specification is stored as double.

3. Final Answer:

   double -> Option D

4. Quick Check:

   Default numeric type = double [OK]

Hint: Remember: MATLAB defaults to double unless specified [OK]

Common Mistakes:

• Thinking single is default
• Confusing integer types as default
• Assuming uint8 is default

2. Which of the following is the correct way to create a single precision number with value 3.14 in MATLAB?

easy

A. x = single(3.14);

B. x = double(3.14);

C. x = int32(3.14);

D. x = single '3.14';

Solution

1. Step 1: Identify correct syntax for single precision

   Use the function single() with a numeric argument to create a single precision number.

2. Step 2: Check each option

   x = single(3.14); uses single(3.14) which is correct syntax. x = double(3.14); creates double, not single. x = int32(3.14); creates integer, which truncates decimals. x = single '3.14'; is invalid syntax.

3. Final Answer:

   x = single(3.14); -> Option A

4. Quick Check:

   Use single() function for single precision [OK]

Hint: Use single() function to convert numbers to single [OK]

Common Mistakes:

• Using double() instead of single()
• Trying to assign string to single
• Using int32 for decimals

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

x = int8(127); y = x + 1; disp(y);

medium

A. -128

B. 128

C. Error: Overflow

D. 127

Solution

1. Step 1: Understand int8 range

   int8 stores integers from -128 to 127. Adding 1 to 127 causes overflow.

2. Step 2: Check overflow behavior

   In MATLAB, int8 overflow wraps around to the minimum value, so 127 + 1 becomes -128.

3. Final Answer:

   -128 -> Option A

4. Quick Check:

   int8 overflow wraps to -128 [OK]

Hint: int8 max is 127; adding 1 wraps to -128 [OK]

Common Mistakes:

• Expecting 128 (out of range)
• Expecting error on overflow
• Thinking value stays at 127

4. Consider this MATLAB code:

a = single(1.5); b = int16(a); disp(b);

What is the output and why?

medium

A. 1.5

B. 1

C. 2

D. Error: Cannot convert single to int16

Solution

1. Step 1: Convert single to int16 behavior

   When converting from single to int16, MATLAB truncates the decimal part (does not round).

2. Step 2: Apply truncation to 1.5

   Truncating 1.5 results in 1, so b becomes 1.

3. Final Answer:

   1 -> Option B

4. Quick Check:

   Conversion truncates decimals, so 1.5 -> 1 [OK]

Hint: Conversion truncates decimals, no rounding [OK]

Common Mistakes:

• Expecting rounding to 2
• Expecting error on conversion
• Expecting output as 1.5

5. You want to store a large array of numbers between 0 and 255 efficiently in MATLAB. Which numeric type should you choose to minimize memory while preserving all values exactly?

hard

A. double

B. single

C. uint8

D. int16

Solution

1. Step 1: Identify value range and memory needs

   Values are between 0 and 255, so an unsigned 8-bit integer (uint8) fits exactly.

2. Step 2: Compare types for memory and precision

   double and single use more memory and are floating-point. int16 uses 16 bits and allows negative values, wasting space.

3. Step 3: Choose the best type

   uint8 uses 8 bits, stores 0-255 exactly, and saves memory.

4. Final Answer:

   uint8 -> Option C

5. Quick Check:

   Use uint8 for 0-255 integer range to save memory [OK]

Hint: Use uint8 for 0-255 integers to save memory [OK]

Common Mistakes:

• Choosing double wastes memory
• Using int16 wastes space and allows negatives
• Using single loses integer precision