Recently while cleaning out some of my old files I came across a PHP class project which I, like every programmer, had started but never finished. I started this class about 3 years ago with intentions of building a larger library of functions which could solve different Leaving Cert maths problems. I never was the best at maths and so I combined something I love, programming, with something I needed to improve, maths! I figured that if I could program a machine to solve the equations I could do it myself. Even though I only wrote one function, it helped me dramatically. Here is a live AJAX demo of the code, and below that is the source code, though I wrote it almost 3 years so do forgive any mistakes or bad code. Just thought I would share it.

You most put spaces between numbers/operators like in the example below for it to work. Also it will only work with X not any other letter. – NOTE: This code is 3 years old

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Source Code

class algebra{

public function solve_x($sum)
{
// checks if sum exists
	if($sum)
	{

		$sum = str_replace("\n", "{line_break}", $sum);
		$sum = split('{line_break}',$sum);
		$chr_no = strlen($sum[0]);
		$sum_array = split(' ',$sum[0]);

	$i = 0;

	while($i < $chr_no)
	{
			$haystack_operators = array('+','-');

			// check to see if $sum_array[$i] is a number//
			if(is_numeric($sum_array[$i])){

				$a = $i - 1;

				$haystack_operators = array('=');

					if(!in_array($sum_array[$a],$haystack_operators ))
					{
						// changes the sign
						if($sum_array[$a] == "-")
						{
							$sign =  "+";
						}
						else
						{
							$sign =  "-";
						};

						$cal[$i] = $sign.$sum_array[$i];
					}
					else
					{
						$theSumOf = $sum_array[$i];
					};

		};
			$needle_notation = 'x,X';

			if(strpbrk($sum_array[$i],$needle_notation))
				{
				// removes the x from the equestion eg 2x -> 2
				$diviser[$i] = str_replace($needle_notation," ",$sum_array[$i]);
				};

			$i++;
		};

			if($cal)
			{
				$calu = array_sum($cal);
			};

			if($diviser)
			{
				$diviser = array_sum($diviser);
			};

			$theSumOf = $theSumOf+$calu;

			if($diviser)
			{
				$ans = $theSumOf/$diviser;
			};

				return $ans;
		};

	}// End of method

}// End of class