/**
* Check norm of difference of "matrices".
* @param matrix $X
* @param matrix $Y
*/
function checkMatrices($X = null, $Y = null)
{
if ($X == null || $Y == null) {
return false;
}
$eps = pow(2.0, -52.0);
if ($X->norm1() == 0.0 & $Y->norm1() < 10 * $eps) {
return true;
}
if ($Y->norm1() == 0.0 & $X->norm1() < 10 * $eps) {
return true;
}
$A = $X->minus($Y);
if ($A->norm1() > 1000 * $eps * max($X->norm1(), $Y->norm1())) {
die("The norm of (X-Y) is too large: " . $A->norm1());
} else {
return true;
}
}
