public function inverse($p)
{
$DEL_TOL = 1.0E-14;
$lon = $p->x / $this->C;
$lat = $p->y;
$num = pow(tan(0.5 * $lat + Sourcemap_Proj::FORTPI) / $this->K, 1.0 / $this->C);
for ($i = Sourcemap_Proj::MAX_ITER; $i > 0; --$i) {
$lat = 2.0 * atan($num * Sourcemap_Proj::srat($this->e * sin($p->y), -0.5 * $this->e)) - Sourcemap_Proj::HALF_PI;
if (abs($lat - $p->y) < $DEL_TOL) {
break;
}
$p->y = $lat;
}
/* convergence failed */
if (!$i) {
throw new Exception("Convergence failed.");
}
$p->x = $lon;
$p->y = $lat;
return $p;
}
