geography_expand()

Datum geography_expand

(

PG_FUNCTION_ARGS

)

Definition at line 463 of file geography_measurement.c.

{
        GSERIALIZED *g = NULL;
        GSERIALIZED *g_out = NULL;
        double unit_distance, distance;
 
        /* Get a wholly-owned pointer to the geography */
        g = PG_GETARG_GSERIALIZED_P_COPY(0);
 
        /* Read our distance value and normalize to unit-sphere. */
        distance = PG_GETARG_FLOAT8(1);
        /* Magic 1% expansion is to bridge difference between potential */
        /* spheroidal input distance and fact that expanded box filter is */
        /* calculated on sphere */
        unit_distance = 1.01 * distance / WGS84_RADIUS;
 
        /* Try the expansion */
        g_out = gserialized_expand(g, unit_distance);
 
        /* If the expansion fails, the return our input */
        if ( g_out == NULL )
        {
                PG_RETURN_POINTER(g);
        }
 
        if ( g_out != g )
        {
                pfree(g);
        }
 
        PG_RETURN_POINTER(g_out);
}

References distance(), gserialized_expand(), and WGS84_RADIUS.

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