function polyregression($x, $y, $n)
{
$m = array();
for ($i = 0; $i < count($x); $i++) {
$m[$i][0] = 1;
for ($j = 1; $j <= $n; $j++) {
$m[$i][$j] = $m[$i][$j - 1] * $x[$i];
}
}
$m = matrixsolve(matrixprod(matrixtranspose($m), $m), matrixprod(matrixtranspose($m), matrix($y, count($y), 1)));
$m = matrixtranspose($m);
return $m[0];
}
function veccomparesamespan($a, $b)
{
if (count($a) != count($b)) {
return false;
}
include_once "matrix.php";
if ($b === null) {
return 0;
}
foreach ($b as $k => $bv) {
if (is_array($bv)) {
continue;
}
if ($bv[0] == '[') {
//in matrix notation
$b[$k] = explode(',', str_replace(array('[', ']', '(', ')'), '', $bv));
} else {
//in compressed notation
$b[$k] = explode('|', $bv);
}
}
foreach ($a as $av) {
$b[] = $av;
}
$s = matrixreduce(matrixtranspose($b), true);
$n = matrixnumsolutions($s, count($a));
return count($a) == $n;
}
