Fraction math functions

This script adds some basic math functions to php allowing you to get percentages, ratios and other fraction based functions.

Background

I created this because I had a need for some math functions that php does not provide. I also made them for my math class to save on time from having to do the fraction conversions myself or to figure grade percents.

The Code

These functions will help with some math related tasks. The greaterThanBy() and lessThanBy will return true, false, or NaN. They were made so you can check if a guessed number is higher or lower by a certain amount set by you. The ratio() function is for those who would make a rpg system or getting your kill to death ratio in a MMO or call of duty. I've included turning a percent into a decimal, improper fraction into mixed number, mixed number into improper fraction with decimal value optional, if a number is between two numbers, and percentage of.

PHP:

<?php
$NaN = "NaN";
//checks if a number is greater than another number by a certain amount
function greaterThanBy($origNum,$testNum,$diff)
{
//define globals
    global $NaN;
    
//check if all values are a number and if not return NaN
    if(!is_numeric($origNum) && !is_numeric($testNum) && !is_numeric($diff))
    {
//not numeric return error
        return $NaN;        
    }
    else
    {
// values are numeric return boolean
        if($origNum > $testNum || $origNum == $testNum)
        {
// original number is higher then the guessed number return false
            return false;
        }
        else
        {
//perfect conditions have been met set variable with value of difference of the two numbers            
            $difference = $testNum - $origNum;    
            if($difference != $diff)
            {
//number is not equal to the estimated number                
                return false;    
            }
            else
            {
// number is equal to the estimated difference            
                return true;    
            }
        }
    }
}
// evaluates if the number is less that the other by a set amount
function lessThanBy($origNum,$testNum,$diff)
{
    global $NaN;
    if(!is_numeric($origNum) && !is_numeric($testNum) && !is_numeric($diff))
    {
        return $NaN;    
    }
    else
    {
        if($origNum < $testNum || $origNum == $testNum)
        {
            return false;
        }
        else
        {
            $difference = $origNum - $testNum;    
            if($difference != $diff)
            {    
                return false;    
            }
            else
            {
                return true;    
            }
        }
    }
}
// checks if the number is between to other numbers
function numberIsBetween($startNum,$testNum,$endNum)
{
    global $NaN;
    if(!is_numeric($startNum) && !is_numeric($testNum) && !is_numeric($endNum))
    {        
        echo $NaN;    
    }
    else
    {
        if($testNum > $endNum || $testNum < $startNum)
        {        
            return false;    
        }
        else if($testNum == $startNum || $testNum == $endNum)
        {
            return false;
            
        }
        else
        {
            if($testNum > $startNum && $testNum < $endNum)
            {                
                return true;    
            }
            else
            {
                return false;    
            }
        }
    }
}
// returns the sum of an array of numbers
function sum($nums)
{
    $numArray = func_get_args();
    if(!is_array($numArray))
    {
        return 0;    
    }
    else
    {    
        return array_sum($numArray);    
    }
}
//returns the percent of a number
function percent($num,$den, $round = "true")
{
    if(!is_numeric($num) && !is_numeric($den))
    {        
        return 0;
    }
    else
    {    
        $per = ($num / $den) * 100;    
        if($round == "true" || strtolower($round) == "true")
        {
            return round($per);    
        }
        else
        {
            return floor($per);    
        }
    }
}
// get reverse percentage gets the number that would make blank percent from another number
function percentageOf($percent,$baseNum)
{
    if(!is_numeric($percent) || !is_numeric($baseNum))
    {        
        return 0;    
    }
    else
    {
        $num = ($percent / 100) * $baseNum;    
        if($round == "true" || strtolower($round) == "true")
        {
            return round($num);    
        }
        else
        {
            return floor($num);    
        }
    }
}
function ratio($k,$d,$round = "true")
{
    if(!is_numeric($k) && !is_numeric($d))
    {
        return 0;        
    }
    else
    {
        $ratio = $k / $d;    
        if($round == "true" || strtolower($round) == "true")
        {
            return round($ratio,2);    
        }
        else
        {
            return $ratio;    
        }
    }
}
function amountLessThan($firstNum,$secNum)
{
    if(!is_numeric($firstNum) && !is_numeric($secNum))
    {        
        return 0;    
    }
    else
    {
        if($firstNum <= $secNum)
        {        
            return 0;
        }
        else
        {    
            $diff = $firstNum - $secNum;    
            return $diff;
        }
    }
}
function amountGreaterThan($firstNum,$secNum)
{
    if(!is_numeric($firstNum) && !is_numeric($secNum))
    {
        return 0;    
    }
    else
    {
        if($firstNum >= $secNum)
        {        
            return 0;
        }
        else
        {            
            $diff = $secNum - $firstNum;
            return $diff;    
        }
    }
}
function percentToDecimal($per)
{
    if(!is_numeric($per))
    {
        return 0;    
    }
    else
    {
        $dec = $per / 100;
        return $dec;
    }    
}
function mixedNumberToImproperFraction($wholeNum,$num,$den,$decimal = 0)
{
    if(is_numeric($wholeNum) && !is_numeric($num) && !is_numeric($den))
    {
        return 0;
    }
    else
    {
        $imFrac = ($wholeNum * $den) + $num;
        if($decimal == 0)
        {
            $result = "$imFrac" . "/" . "$den";
            return $result;
        }
        else
        {
            return $imFrac / $den;    
        }
    }    
}
function improperFractionToMixedNumber($num,$den)
{
    if(!is_numeric($num) && !is_numeric($den))
    {
        return 0;
    }
    else
    {
        if($num < $den)
        {
            return 0;    
        }
        else
        {
            $wholeNum = floor($num / $den);
            $dem = $wholeNum * $den;
            $newNum = $num - $dem;
            $result = "$wholeNum" . " " . "$newNum" . "/" . "$den";
            return $result;    
        }    
    }
}
function decimalToPercent($dec)
{    
    if(!is_numeric($dec))
    {
        return 0;    
    }
    else
    {
        $per = $dec * 100;
        return $per;    
    }    
}
?>