sqrt

add a note User Contributed Notes

30-Mar-2006 04:03


A much easier way to find perfect squares:

This method uses integer roots to find perfect squares instead of integer squares to find integer roots.



<?



# initial value

$i = 0;



#set any limit you want

$setSomeLimit = 10000;



# do it! .... do it! ... do it!

for ($n = 1; $n < sqrt($setSomeLimit; $n++)

{

    // Find the square

    $s= $n * $n;



    print "<br>perfect_square_root is of $s is $n";

}



?>

php NOSPAM at primezero dot com
13-Jul-2005 10:15


creating perfect squares... (no decimals)



<?



# initial value

$i = 0;



#set any limit you want

$setSomeLimit = 10000;



# do it! .... do it! ... do it!

do {



   # find the square root

   $sqRoot  = sqrt($i);

   

   # not a decimal? that it is a perfect square! ^_^

   if ( ereg ("^[0-9]{1,12}$", $sqRoot)) {

   

       # suppose that the_square_root = teh_square_root

       print "<br>perfect_square_root is of $i is $sqRoot";

   }

$i++; # next!! 



# keeps running until it reaches the limit

} while ($i < $setSomeLimit);



?>

btharper1221 at gmail dot com
15-May-2005 11:48


this is something you can use if you need an exact answer to a root problem, this includes an echo outside of the function to show how it works, it will return it such as

$ret[0] is the number still part of the root (this is the exactness part of it)

$ret[1] is the number of roots and 

$ret[2] is 1 or 0, 1 being that there should be an i following the number of roots (imaginary)



<?php

function newrt($val,$rt){

$i = 0;

if(($rt % 2 == 0) && ($val < 1)){

$i = 1;

$val = (-$val);

}

$c = 1;

if(($rt % 2 != 0) && ($val < 0)){

$c = -$c;

$val = -$val;

}

for($d = 2; pow($d,$rt) <= abs($val); $d++){

if($val % (pow($d,$rt)) == 0){

$val = ($val/(pow($d,$rt)));

$c = ($c*$d);

$d--;

}

}

$ret[0] = $val;

$ret[1] = $c;

$ret[2] = $i;

return $ret;

}//end function newrt



$ret = newrt($num,$num2);

if($ret[0] != 1){

if($ret[2] == 0) echo $ret[1]." roots of ".$ret[0];

if($ret[2] == 1) echo $ret[1]."<b><i>i</i></b> roots of ".$ret[0];

}elseif($ret[0] == 1){

if($ret[2] == 0) echo $ret[1];

if($ret[2] == 1) echo "$ret[1]<b><i>i</i></b>";

}

?>

chris DOT rutledge AT gmail DOT com
31-Mar-2005 06:24


Just a note to say you can take the square root of a negative number - it returns an imaginary number.



One might do it like this



//take initial value of $x



$abs_x = abs($x);

$answer = sqrt($abs_x);



echo $answer;



if ($x < 0) echo"<b><i>i</i></b>";

jouhni at web dot de
18-Feb-2005 03:46


To get any root of a number your can use the pow() function:



pow(8, 1/3)



which gives you the third root of eight.



Jouhni

php user
14-May-2004 03:25


How to calculate triangle's area if you haven't height measure.

You need only sides' measure.

it would have to work.



(formula of erone)



$s1 = side 1

$s2 = side 2

$s3 = side 3



<?

function area($s1,$s2,$s3)

{

$calc1 = ($s1+$s2+$s3)/2;

$calc2 = $p*($p-$s1)*($p-$s2)*($p-$s3);

$result = round(sqrt($p),2);

return $result;

}

?>



example of I use:



<?

//This will make to return the area of a triangle with sides of 3,4,5

$area = area(3,4,5);

echo $area;

?>

bishop
18-Jul-2003 01:09


Compute a triangle's area:



function triangleArea($a, $b /* ... */) {

    if (func_num_args() === 3) {

        $s = .5 * ($a + $b + ($c = func_get_arg(2)));

        return sqrt($s * ($s-$a) * ($s-$b) * ($s-$c));

    } else {

        return (.5 * $a * $b);

    }

}



With 2 args, parameters are triangle's base and height.  With 3 args, parameters are the lengths of each side.  Argument order is not important.



Either way, you get the area.

tcn at pandora dot be
14-Nov-2002 04:37


Checking if the square you want to take from a number is valid or not (you can't take the root of a negative number)



if ($i<0)

 {

  echo "Error! The number you specified can't be rooted! It's negative!

  }

  else

  {

  echo "The square root of your number is ".sqrt($i);

  }

morvandiumNOSPAM at yahoo dot com
05-Nov-2001 08:44


I find this useful for any grid system where distances need to be computed (maps and graphs, mostly).





Just use the distance between points formula (pseudo-code): sqrt((x2-x1)^2+(y2-y1)^2) to find the distance between two points.

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