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3.9 Absolute Value

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3.9 Absolute Value

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The absolute value of a number is its distance from zero on the number line, regardless of its direction.

Absolute values are always non-negative.

For example:

  • The absolute value of 10 is 10.
  • The absolute value of -10 is also 10.
  • The absolute value of 0 is 0.

In Python, the built-in abs() function is used to find the absolute value of a number.


Syntax #

abs(number)

Parameters #

Parameter Description
number An integer, floating-point number, or complex number.

Return Value #

Returns the absolute value of the given number.


Example 1: Absolute Value of a Positive Integer #

main.py

number = 25

print(abs(number))

Output #

25

Explanation #

  • 25 is already positive.
  • Therefore, its absolute value is 25.

Example 2: Absolute Value of a Negative Integer #

main.py

number = -25

print(abs(number))

Output #

25

Explanation #

  • -25 is 25 units away from zero.
  • The abs() function removes the negative sign.
  • The result is 25.

Example 3: Absolute Value of Zero #

main.py

number = 0

print(abs(number))

Output #

0

Explanation #

  • Zero is neither positive nor negative.
  • Its distance from zero is zero.
  • Therefore, the absolute value is 0.

Example 4: Absolute Value of a Float #

main.py

temperature = -18.75

print(abs(temperature))

Output #

18.75

Explanation #

  • The abs() function also works with floating-point numbers.
  • The negative sign is removed.
  • The decimal value remains unchanged.

Example 5: Absolute Value in a Calculation #

main.py

difference = 75 - 100

print(difference)
print(abs(difference))

Output #

-25
25

Explanation #

  • The subtraction produces -25.
  • The abs() function converts it to its absolute value.
  • This is useful when only the magnitude of a difference is important.

Example 6: Absolute Value of a Complex Number #

main.py

number = 3 + 4j

print(abs(number))

Output #

5.0

Explanation #

  • For complex numbers, abs() returns the magnitude (also called the modulus).
  • For 3 + 4j, the magnitude is 5.0.
  • The returned value is a floating-point number.

Example 7: User Input #

main.py

number = int(input("Enter an integer: "))

print(abs(number))

Sample Input #

-45

Output #

45

Explanation #

  • The user enters a negative integer.
  • int() converts the input into an integer.
  • abs() returns its absolute value.

Example 8: Comparing Two Numbers #

main.py

a = 12
b = 20

difference = abs(a - b)

print(difference)

Output #

8

Explanation #

  • a - b evaluates to -8.
  • abs() converts it to 8.
  • This gives the distance between the two numbers.

Example 9: Absolute Value Inside an Expression #

main.py

result = abs(-15) + abs(-20)

print(result)

Output #

35

Explanation #

  • abs(-15) returns 15.
  • abs(-20) returns 20.
  • Their sum is 35.

Example 10: Checking the Return Type #

main.py

print(type(abs(-50)))
print(type(abs(-4.5)))

Output #

<class 'int'>
<class 'float'>

Explanation #

  • The return type depends on the input.
  • An integer input returns an integer.
  • A floating-point input returns a floating-point value.

Common Mistakes #

1. Assuming abs() Always Returns an Integer #

Incorrect

print(type(abs(-4.5)))

Incorrect Expectation #

<class 'int'>

Actual Output #

<class 'float'>

Reason

abs() returns the same numeric type as its argument (except for complex numbers, where it returns a float).


2. Forgetting Parentheses #

Incorrect

number = -15

print(abs)

Output #

<built-in function abs>

Reason

abs is the function object itself.

Correct

print(abs(number))

3. Passing a String Directly #

Incorrect

print(abs("-25"))

Output #

TypeError: bad operand type for abs(): 'str'

Reason

abs() expects a numeric value.

Correct

print(abs(int("-25")))

4. Expecting the Original Variable to Change #

Incorrect

number = -10

abs(number)

print(number)

Output #

-10

Reason

abs() returns a new value.
It does not modify the original variable.

Correct

number = abs(number)

print(number)

Best Practices #

  • Use abs() whenever you need the magnitude of a number.
  • Store the returned value if it will be used later.
  • Convert user input to a numeric type before calling abs().
  • Use abs(a - b) when calculating the difference between two values.
  • Remember that abs() works with integers, floating-point numbers, and complex numbers.

Key Points to Remember #

  • The absolute value is the distance of a number from zero.
  • Absolute values are always non-negative.
  • Python provides the built-in abs() function.
  • abs() works with integers, floating-point numbers, and complex numbers.
  • For complex numbers, abs() returns the magnitude.
  • abs() returns a new value and does not modify the original variable.
  • The return type depends on the type of the input value.

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