deltaLongitude()

double deltaLongitude	(	double	azimuth,
		double	sigma,
		double	tsm,
		SPHEROID *	sphere
	)

Definition at line 143 of file lwgeom_spheroid.c.

References SPHEROID::f.

Referenced by distance_ellipse_calculation(), and spheroid_parallel_arc_length().

{
        /* compute the expansion C */
        double das,C;
        double ctsm,DL;

        das = cos(azimuth)*cos(azimuth);
        C = sphere->f/16.0 * das * (4.0 + sphere->f * (4.0 - 3.0 * das));

        /* compute the difference in longitude */
        ctsm = cos(tsm);
        DL = ctsm + C * cos(sigma) * (-1.0 + 2.0 * ctsm*ctsm);
        DL = sigma + C * sin(sigma) * DL;
        return (1.0 - C) * sphere->f * sin(azimuth) * DL;
}

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