in php how can i check how close to a square an image is?

Question

here is what i have so far. i am not sure if it's accurate, and even if it is, is there a better way to do this? i want to check images and determine if it's tall, wide, square, or kind of square. then i want to place a class name on the div wrapping the image. kind of square is blank (no class name), a tall image has class name of tall, a wide image has class name of wide, and a square image has class name of big. i put the variables in the alt parameter of image to see what's going on to then make any needed adjustments/tweaks.

<?php
function Hypotenuse($side1, $side2)
{
    return sqrt(($side1 * $side1) + ($side2 * $side2));
}
$class="";
$subtraction="";
$result="";
$percent=0;
$image_info = getimagesize("path/image.png");
$image_width = $image_info[0];
$image_height = $image_info[1];
if ($image_width>$image_height){ //wide image
    $class="wide";
    $subtraction=$image_width-$image_height;
} else { //tall image
    $class="tall";
    $subtraction=$image_height-$image_width;
}
$result = Hypotenuse($image_width, $image_height);
if ($subtraction>0) {
    $percent = $subtraction/$result * 100;
} else {
    $percent = 0/$result * 100;
}
//if ($subtraction<200) //old way
if ($percent<19) //close to being a square
{
    $class="";
}
if ($image_width==$image_height){ //an exact square
    $class="big";
}
?>
<div class="<?php echo $class; ?>">
    <img src="path/image.png" alt="<?php echo $image_width."x".$image_height.", ".$subtraction.", ".$result.", ".$percent; ?>" />
</div>

EDIT: here is new script. is this better? the stuff before and after this is still the same.

if ($image_width==$image_height){ //an exact square
    $class="big";
} else {
    if ($image_width>$image_height){ //wide image
        $class="wide";
        $subtraction=$image_width-$image_height;
    } else { //tall image
        $class="tall";
        $subtraction=$image_height-$image_width;
    }
    $result = Hypotenuse($image_width, $image_height);
    $percent = $subtraction/$result * 100;
    if ($percent<19) { //close to being a square
        $class="";
    }
}

Answer 1

Here's the same PHP logic, just reorganised a little for clarity:

$image_info = getimagesize("path/image.png");
$image_width = $image_info[0];
$image_height = $image_info[1];

if ($image_width == $image_height) { //an exact square
    $class = 'big';
} else {
    $subtraction = abs($image_height - $image_width);
    $hypotenuse = sqrt($image_width ** 2 + $image_height ** 2);
    $percent = $subtraction / $hypotenuse * 100;

    if ($percent < 19) { //close to being a square
        $class = '';
    } else {
        $class = ($image_width > $image_height) ? 'wide' : 'tall';
    }
}