Numeric types (double, single, integer) in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a variable x as a double precision number with value 5.

MATLAB

x = [1](5);

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

Adouble

Bsingle

Cint32

Duint8

Attempts:

3 left

💡 Hint

Common Mistakes

Using integer types like int32 or uint8 when a floating-point number is needed.

In MATLAB, double is the default numeric type for floating-point numbers. Using double(5) creates a double precision number.

2fill in blank

medium

Complete the code to create a variable y as a single precision number with value 3.14.

MATLAB

y = [1](3.14);

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

Aint16

Buint32

Csingle

Ddouble

Attempts:

3 left

💡 Hint

Common Mistakes

Using double instead of single.

The single function converts a number to single precision floating-point format.

3fill in blank

hard

Fix the error in the code to create an integer variable z with value 10 using the correct integer type.

MATLAB

z = [1](10);

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

Adouble

Bint32

Csingle

Dfloat

Attempts:

3 left

💡 Hint

Common Mistakes

Using floating-point types like single or double instead of integer types.

To create a 32-bit integer in MATLAB, use int32. The other options are either floating-point types or invalid in MATLAB.

4fill in blank

hard

Fill both blanks to create a variable a as a single precision number and a variable b as an unsigned 8-bit integer.

MATLAB

a = [1](7.5);
b = [2](255);

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

Asingle

Bint16

Cuint8

Ddouble

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up signed and unsigned integer types.

a is created as single precision using single. b is created as an unsigned 8-bit integer using uint8.

5fill in blank

hard

Fill all three blanks to create a dictionary (struct) data with keys val1, val2, and val3 storing a double, a single, and an int16 value respectively.

MATLAB

data.val1 = [1](1.23);
data.val2 = [2](4.56);
data.val3 = [3](100);

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

Adouble

Bsingle

Cint16

Duint32

Attempts:

3 left

💡 Hint

Common Mistakes

Using unsigned integer types instead of signed for int16.

val1 is double precision, val2 is single precision, and val3 is a 16-bit signed integer.

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