^ as pow()

[jurii]

Hello all,

I tried to code a script, that parses ^ (or any other symbol) as power. E.g. "2^x" should become "pow(2,x)". This wouldn't be so difficult, but it should also work with nested functions, like change "2(1+x)^(x-1)+1" into "2pow((1+x),(x-1))+1" , "x^yz" into "pow(x,pow(y,z))", "sin(x)^cos(x)" into "pow(sin(x),cos(x))" and so on, even highly complex nested funstions. This took me several hours until I realized I couldn't make it.

So does anybody know a free script that can exactly do this?

Thank you very much!

[god0fgod]

function powers($a,$b){
for($x = 0; $x < $b;$x++){
$a *= $a;
}
}

pow() is a already a function. It does the exact above.

[jurii]

I know ...

I want a parser that turns $a^$b into a power function.

Input: x^y
Output: pow(x,y)

So a lot of string operations ...

[bpat1434]

Well, easily enough you could do:

<?php

$x = 5;
$y = 2;
$z = 10;

$string = "$x^$y";

$pattern = "~([^^]+)^(.*)~U";
preg_match_all($pattern, $string, $matches);

echo 'pow(' . $matches[1][0] . ', ' . $matches[1][1] . ') = ';
echo pow($matches[1][0], $matches[1][1]);

Something like that should get you started... but as you get more and more intricate, it can get tricky.

[jurii]

Please folks, I don't need help how to get started. I already started pretty good until it got really, really intricate. So I'm only asking: does anybody know a free script that can do this?

[bpat1434]

No, I don't know of a free script that can do this. However, if you learn regular expressions, it can be done. Weedpacket is pretty good with them usually. Not sure if something this intricate would be possible though. You'd have to really think about it, especially when order of operations comes into play, as well as manual parenthesis so that one expression is evaluated before another.