I have 6 nested loops in a PHP program, however, the calculation time for the script is extremely slow. I would like to ask if there is a better way of implementing the 6 loops and increasing computation time, even if it means switching to another language. The nature of the algorithm I'm implementing requires iteration, so I don't know how I can better implement it.
Here's the code.
<?php
$time1 = microtime(true);
$res = 16;
$imageres = 128;
for($x=0;$x<$imageres;++$x){
for($y=0;$y<$imageres;++$y){
$pixels[$x][$y]=1;
}};
$quantizermatrix = 1;
$scalingcoefficient = 1/($res/2);
for($currentimagex=0;$currentimagex<($res*($imageres/$res-1)+1);$currentimagex = $currentimagex +$res){
for($currentimagey=0;$currentimagey<($res*($imageres/$res-1)+1);$currentimagey = $currentimagey +$res){
for($u=0;$u<$res;++$u){
for($v=0;$v<$res;++$v){
for($x=0;$x<$res;++$x){
for($y=0;$y<$res;++$y){
if($u == 0) {$a = 1/(sqrt(2));} else{$a = 1;};
if($v == 0){$b = 1/(sqrt(2));}else{$b = 1;};
$xes[$y] = $pixels[$x+$currentimagex][$y+$currentimagey]*cos((M_PI/$res)*($x+0.5)*$u)*cos( M_PI/$res*($y+0.5)*$v);
}
$xes1[$x] = array_sum($xes);
}
$xes2= array_sum($xes1)*$scalingcoefficient*$a*$b;
$dctarray[$u+$currentimagex][$v+$currentimagey] = round($xes2/$quantizermatrix)*$quantizermatrix;
}}}};
foreach($dctarray as $dct){
foreach($dct as $dc){
echo $dc." ";
}
echo "<br>";}
$time2 = microtime(true);echo 'script execution time: ' . ($time2 - $time1);
?>
I've removed a large portion of the code that's irrelevant, since this is the section of the code that's problematic
Essentially the code iterates through every pixel in a PNG image and outputs a computed matrix (2d array). This code takes around 2 seconds for a 128x128 image. This makes this program impractical for normal images greater than 128x128
