# Cramers Rule

By Craig
on January 8, 2005

Version: 1.0.0

Type: Full Script

Category: Math Functions

Description: This is a php function that will let you quickly solve the following types of problems as well as display what was done to find the answer (all problems are algebra math level or above):
Substitution
Elemination

```Format:<br>
Ax + By = E<br>
Cx + Dy = F<br>
Where A-F = already known numbers preceding variables<br>
and x-y = the variables you're want to find the value of.
<?
function calc(\$a, \$b, \$c, \$d, \$e, \$f){
\$numbers = array(1 => \$a, 2 => \$b, 3 => \$c, 4 => \$d, 5 => \$e, 6 => \$f);

for(\$x=1; \$x < 7; \$x++){
\$slash = strpos(\$numbers[\$x], "/");
if(\$slash !== false){
list(\$y, \$z) = explode("/", \$numbers[\$x]);
\$numbers[\$x] = \$y / \$z;
\$numbers[\$x] = round(\$numbers[\$x], 20);
}
}
\$answer[0] = (\$numbers[1] * \$numbers[4]) - (\$numbers[3] * \$numbers[2]);
echo "\$numbers[1] \$numbers[2]<br>
\$numbers[3] \$numbers[4]<br>";

\$answer[0] = (\$numbers[5] * \$numbers[4]) - (\$numbers[6] * \$numbers[2]);
echo "\$numbers[5] \$numbers[2]<br>
\$numbers[6] \$numbers[4]<br>";

\$answer[0] = (\$numbers[1] * \$numbers[6]) - (\$numbers[3] * \$numbers[5]);
echo "\$numbers[1] \$numbers[5]<br>
\$numbers[3] \$numbers[6]<br>";

die("Invalid Input, A-D cannot equal 0");
}

}
?>
<form method=POST action="z_calc.php" name="calculator">
<table>
<tr>
<td>A:</td>
<td>
<input type="text" name="a">
</td>
<td>B:</td>
<td>
<input type="text" name="b">
</td>
<td rowspan=2>=<br>=</td>
<td>E:</td>
<td>
<input type="text" name="e">
</td>
</tr>
<tr>
<td height="26">C:</td>
<td>
<input type="text" name="c">
</td>
<td>D:</td>
<td>
<input type="text" name="d">
</td>
<td>F:</td>
<td>
<input type="text" name="f">
</td>
</tr>
<tr>
<td colspan=7 align="center">
<input type="submit" name="submit" value="Submit">
<input type="reset" value="Reset">
</td>
</tr>
</table>
</form>
<?
if(isset(\$_POST['submit'])){
calc(\$_POST['a'], \$_POST['b'], \$_POST['c'], \$_POST['d'], \$_POST['e'], \$_POST['f']);
}
?>```
﻿