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   "source": [
    "### <center>San Jose State University<br>Department of Applied Data Science<br><br>**DATA 200<br>Computational Programming for Data Analytics**<br><br>Spring 2024<br>Instructor: Ron Mak</center>"
   ]
  },
  {
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   "metadata": {},
   "source": [
    "# 4.3 Functions with Multiple Parameters"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Functions with Multiple Paraemters.\n",
    "#### A function can have any number of parameters, including no parameters. For example:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def maximum(value1, value2, value3):\n",
    "    \"\"\"Return the maximum of three values.\"\"\"\n",
    "    max_value = value1\n",
    "    \n",
    "    if value2 > max_value:\n",
    "        max_value = value2\n",
    "    if value3 > max_value:\n",
    "        max_value = value3\n",
    "        \n",
    "    return max_value"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "maximum(12, 27, 36)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "maximum(12.3, 45.6, 9.7)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "maximum('yellow', 'red', 'orange')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "maximum(13.5, -3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Local Variables\n",
    "#### Inside our custom `maximum()` function, we introduced the variable `max_value`. This variable is **local** to the function. We cannot access it outside of the function:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "max_value"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "max_value = 7"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "max_value"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### If there were a variable also named `max_value` defined outside the function, it would be a totally different variable, as if it had a different name."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Multiple Return Values\n",
    "\n",
    "#### A function can return more than one return value. We can optionally parenthesize the values, and they are implicitly packed into a **tuple**. After calling such a function, **unpack** the returned tuple by assigning the returned values to multiple variables at once (as many variables as there are values in the tuple)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def square_and_cube(n):\n",
    "    \"\"\"\n",
    "    Return the square and the cube of the value of parameter n.\n",
    "    \"\"\"\n",
    "    return n*n, n*n*n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "x = 3.14159\n",
    "square, cube = square_and_cube(x)\n",
    "\n",
    "print(f'The square and cube of {x} are {square:6.4f} and {cube:6.4f}')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Python’s Built-In max and min Functions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "min('yellow', 'red', 'orange', 'blue', 'green')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "min(15, 9, 27, 14)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### **EXAMPLE:** Call function `max()` with the list `[14, 27, 5, 3]` as an argument. What is the result?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "max([14, 27, 5, 3])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### **EXAMPLE:** Call function `min()` with the string `'orange'` as an argument. What is the result?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "min('orange')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Function Terminology from Computer Science\n",
    "#### In computer science literature, several terms refer to the parameters listed in parentheses in the function header, such as `value1`, `value2`, and `value3` of our custom `maximum()` function:\n",
    "- #### parameters\n",
    "- #### formal parameters\n",
    "- #### formal arguments\n",
    "\n",
    "#### When we call a function, the arguments we list in parentheses such as `15`, `9`, `27`, and `14` after the name of a function are refered to by several terms:\n",
    "- #### arguments\n",
    "- #### actual arguments\n",
    "- #### actual parameters\n",
    "\n",
    "#### Not to be overly pedantic and to avoid unnecessary confusion, let's simply use the term **parameters** in the function definition and **arguments** in the function call."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "##########################################################################\n",
    "# (C) Copyright 2019 by Deitel & Associates, Inc. and                    #\n",
    "# Pearson Education, Inc. All Rights Reserved.                           #\n",
    "#                                                                        #\n",
    "# DISCLAIMER: The authors and publisher of this book have used their     #\n",
    "# best efforts in preparing the book. These efforts include the          #\n",
    "# development, research, and testing of the theories and programs        #\n",
    "# to determine their effectiveness. The authors and publisher make       #\n",
    "# no warranty of any kind, expressed or implied, with regard to these    #\n",
    "# programs or to the documentation contained in these books. The authors #\n",
    "# and publisher shall not be liable in any event for incidental or       #\n",
    "# consequential damages in connection with, or arising out of, the       #\n",
    "# furnishing, performance, or use of these programs.                     #\n",
    "##########################################################################\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Additional material (C) Copyright 2023 by Ronald Mak"
   ]
  }
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