## PHP algebraic equation function

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

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