# 4.3 Functions with Multiple Parameters¶

- `maximum` function that determines and returns the largest of three values.

In [1]:

    def maximum(value1, value2, value3):
        """Return the maximum of three values."""
        max_value = value1
        if value2 > max_value:
            max_value = value2
        if value3 > max_value:
            max_value = value3
        return max_value

In [2]:

    maximum(12, 27, 36)

Out[2]:

    36

In [3]:

    maximum(12.3, 45.6, 9.7)

Out[3]:

    45.6

In [4]:

    maximum('yellow', 'red', 'orange')

Out[4]:

    'yellow'

- We did not place blank lines above and below the `if` statements, because pressing return on a blank line in interactive mode completes the function’s definition.
- May call maximum with mixed types, such as `int`s and `float`s.

In [5]:

    maximum(13.5, -3, 7)

Out[5]:

    13.5

### Function maximum’s Definition¶

- Specify multiple parameters in a comma-separated list.
- To determine the largest value:
  - Assume that `value1` contains the largest value.
  - The first `if` statement then tests `value2 > max_value`, and if this condition is `True` assigns `value2` to `max_value`.
  - The second `if` statement then tests `value3 > max_value`, and if this condition is `True` assigns `value3` to `max_value`.
- Now, `max_value` contains the largest value.

### Python’s Built-In max and min Functions¶

- For many common tasks, the capabilities you need already exist in Python.
- Built-in `max` and `min` functions know how to determine the largest and smallest of their two or more arguments:

In [6]:

    max('yellow', 'red', 'orange', 'blue', 'green')

Out[6]:

    'yellow'

In [7]:

    min(15, 9, 27, 14)

Out[7]:

    9

- Each also can receive an iterable argument, such as a list or a string.
- Using built-in functions or functions from the Python Standard Library’s modules rather than writing your own can reduce development time and increase program reliability, portability and performance.
- Python’s built-in functions and modules

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