function initialLat($North, $n0, $afo, $PHI0, $n, $bfo)
{
/*
Compute initial value for Latitude (PHI) IN RADIANS.
Input: - _
northing of point (North) and northing of false origin (n0) in meters;
semi major axis multiplied by central meridian scale factor (af0) in meters;
latitude of false origin (PHI0) IN RADIANS;
n (computed from a, b and f0)
ellipsoid semi major axis multiplied by central meridian scale factor (bf0) in meters.
*/
//First PHI value (PHI1)
$PHI1 = ($North - $n0) / $afo + $PHI0;
//Calculate M
$M = Marc($bfo, $n, $PHI0, $PHI1);
//Calculate new PHI value (PHI2)
$PHI2 = ($North - $n0 - $M) / $afo + $PHI1;
//Iterate to get final value for InitialLat
while (abs($North - $n0 - $M) > 1.0E-5) {
$PHI2 = ($North - $n0 - $M) / $afo + $PHI1;
$M = Marc($bfo, $n, $PHI0, $PHI2);
$PHI1 = $PHI2;
}
return $PHI2;
}
function InitialLat($north, $n0, $af0, $phi0, $n, $bf0)
{
$phi1 = ($north - $n0) / $af0 + $phi0;
$M = Marc($bf0, $n, $phi0, $phi1);
$phi2 = ($north - $n0 - $M) / $af0 + $phi1;
$ind = 0;
while (abs($north - $n0 - $M) > 1.0E-5 && $ind < 20) {
$ind = $ind + 1;
$phi2 = ($north - $n0 - $M) / $af0 + $phi1;
$M = Marc($bf0, $n, $phi0, $phi2);
$phi1 = $phi2;
}
return $phi2;
}
