Sven Dzepina wrote:
Hello people =)
Has somebody a nice script, which can solve equations ?
yes, I do now :-)
It would be super, if someone has an idea where I can get such a script /
code in php.
Use mine
Thanks.
you're welcome :-)))
<?php // solve equation
function solve($eq) {
$eq = str_replace(' ', '', $eq);
// validate expression
$terms = explode('=', $eq);
if (count($terms) != 2) {
return('syntax error: you must have one (and only one) "=" in ['
. $eq . '].');
}
// put rhs in lhs
$eq = $terms[0] . '-(' . $terms[1] . ')';
if (substr_count($eq, '(') != substr_count($eq, ')')) {
return('syntax error: parenthesis mismatch in [' . $eq . '].');
}
if (preg_match('/\([^)]*\(/', $eq)) {
return('syntax error: only one level of parenthesis allowed in ['
. $eq . '].');
}
if (preg_match('/[^x0-9+*\/().=-]/', $eq)) {
return('syntax error: the only valid characters are x, 0-9, +, '
. '*, /, (, ), ., and - in [' . $eq . ']');
}
if (preg_match('/[^x0-9\)][-+\/*]/', $eq)) {
return('syntax error: you can only operate on numbers in ['
. $eq . ']');
}
if (preg_match('/[-+\/*][^x0-9\(]/', $eq)) {
return('syntax error: you can only operate on numbers in ['
. $eq . ']');
}
$eq = str_replace('x', '$x', $eq);
$y0 = $y1 = 0;
$x = 0; eval('$y0 = ' . $eq . ';');
$x = 1; eval('$y1 = ' . $eq . ';');
$slope = $y1 - $y0;
$intersect = $y0;
return (- ($intersect / $slope));
}
$eq = '2 * (x + 4) = 10';
echo $eq, ' ==> x = ', solve($eq), '<br />';
$eq = '(2 * x) + 4 = 10';
echo $eq, ' ==> x = ', solve($eq), '<br />';
$eq = '2 * x + 4 = 10';
echo $eq, ' ==> x = ', solve($eq), '<br />';
$eq = '4 + x / 10 = 2';
echo $eq, ' ==> x = ', solve($eq), '<br />';
?>
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