Equation

[Sven Dzepina]

Hello people =)

Has somebody a nice script, which can solve equations ?
It would be super, if someone has an idea where I can get such a script /
code in php.

Thanks.

Gretting!

[Pedro]

Re: Equation

Sven Dzepina wrote:[color=blue]
>Hello people =)
>
>Has somebody a nice script, which can solve equations ?[/color]

yes, I do now :-)
[color=blue]
>It would be super, if someone has an idea where I can get such a script /
>code in php.[/color]

Use mine
[color=blue]
>Thanks.[/color]

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($e q, ')')) {
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 />';
?>


--
I have a spam filter working.
To mail me include "urkxvq" (with or without the quotes)
in the subject line, or your mail will be ruthlessly discarded.

[Sven Dzepina]

Re: Equation

Big Thanks Pedro!
It's a great script =)

An Equation Script which can handle more variables would be better ;)


"Pedro" <hexkid@hotpop. com> schrieb im Newsbeitrag
news:d2foov8ts7 hjs4as316ki91ts 6erme065m@4ax.c om...[color=blue]
> Sven Dzepina wrote:[color=green]
> >Hello people =)
> >
> >Has somebody a nice script, which can solve equations ?[/color]
>
> yes, I do now :-)
>[color=green]
> >It would be super, if someone has an idea where I can get such a script /
> >code in php.[/color]
>
> Use mine
>[color=green]
> >Thanks.[/color]
>
> 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($e q, ')')) {
> 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 />';
> ?>
>
>
> --
> I have a spam filter working.
> To mail me include "urkxvq" (with or without the quotes)
> in the subject line, or your mail will be ruthlessly discarded.[/color]

[Pedro]

Re: Equation

Sven Dzepina wrote:[color=blue]
> Big Thanks Pedro!
> It's a great script =)[/color]

LOL, thanks

[color=blue]
> An Equation Script which can handle more variables would be better ;)[/color]

Yes, I'm pretty sure it would.
If you can guarantee the equations are normalized

3x - 6 = 0

instead of

4(x-1) = x+2

that makes making the solver script terribly easy for

a) ax+b=0
b) ax^2+bx+c=0
c) ax+by+c=0 (and) dx+ey+f=0
d) ...

Input only the constants ... not the whole equation;
for the equation above you'd input only: a=3, and b=-6

and then solve (after checking for division by zero only):
return -($b/$a);


or, for equation in type 2:
return array((-$b+sqrt($a*$a-4*$a*$c))/(2*$a),
(-$b-sqrt($a*$a-4*$a*$c))/(2*$a));

etc. ... ...



Happy Coding :-)

[Sven Dzepina]

Re: Equation

Hi Pedro,

you must be a very intelligent human =)

Gretting.

"Pedro" <hexkid@hotpop. com> schrieb im Newsbeitrag
news:bmhvt2$n6t dt$1@ID-203069.news.uni-berlin.de...[color=blue]
> Sven Dzepina wrote:[color=green]
> > Big Thanks Pedro!
> > It's a great script =)[/color]
>
> LOL, thanks
>
>[color=green]
> > An Equation Script which can handle more variables would be better ;)[/color]
>
> Yes, I'm pretty sure it would.
> If you can guarantee the equations are normalized
>
> 3x - 6 = 0
>
> instead of
>
> 4(x-1) = x+2
>
> that makes making the solver script terribly easy for
>
> a) ax+b=0
> b) ax^2+bx+c=0
> c) ax+by+c=0 (and) dx+ey+f=0
> d) ...
>
> Input only the constants ... not the whole equation;
> for the equation above you'd input only: a=3, and b=-6
>
> and then solve (after checking for division by zero only):
> return -($b/$a);
>
>
> or, for equation in type 2:
> return array((-$b+sqrt($a*$a-4*$a*$c))/(2*$a),
> (-$b-sqrt($a*$a-4*$a*$c))/(2*$a));
>
> etc. ... ...
>
>
>
> Happy Coding :-)
>[/color]