gistfile1.php

<?php

$string = 'BOX(534927.21 2184044.55,743600 2471494)';

preg_match_all('/(\d+)(?:\.\d+)?/', $string, $matches);

/*
array(2) {
  [0]=>
  array(4) {
    [0]=>
    string(9) "534927.21"
    [1]=>
    string(10) "2184044.55"
    [2]=>
    string(6) "743600"
    [3]=>
    string(7) "2471494"
  }
  [1]=>
  array(4) {
    [0]=>
    string(6) "534927"
    [1]=>
    string(7) "2184044"
    [2]=>
    string(6) "743600"
    [3]=>
    string(7) "2471494"
  }
}