Ellipsoidal distance along meridian
s = meridianarc(phi1,phi2,ellipsoid)
s = meridianarc(phi1,phi2,ellipsoid) calculates the (signed) distance s between latitudes phi1 and phi2 along a meridian on the ellipsoid defined by ellipsoid, which can be a referenceSphere, referenceEllipsoid, or oblateSpheroid object, or a vector of the form [semimajor_axis eccentricity]. Latitudes phi1 and phi2 are in radians. The distance s has the same units as the semimajor axis of the ellipsoid. If phi2 is less than phi1, s is negative.