gidx_inter_volume()

static float gidx_inter_volume ( GIDX *  a, GIDX *  b  )

static

Definition at line 340 of file gserialized_gist_nd.c.

{
        uint32_t i;
        float result;
 
        POSTGIS_DEBUG(5, "entered function");
 
        if (!a || !b)
        {
                elog(ERROR, "gidx_inter_volume received a null argument");
                return 0.0;
        }
 
        if (gidx_is_unknown(a) || gidx_is_unknown(b))
                return 0.0;
 
        /* Ensure 'a' has the most dimensions. */
        gidx_dimensionality_check(&a, &b);
 
        /* Initialize with minimal length of first dimension. */
        result = Min(GIDX_GET_MAX(a, 0), GIDX_GET_MAX(b, 0)) - Max(GIDX_GET_MIN(a, 0), GIDX_GET_MIN(b, 0));
 
        /* If they are disjoint (max < min) then return zero. */
        if (result < 0.0)
                return 0.0;
 
        /* Continue for remaining dimensions. */
        for (i = 1; i < GIDX_NDIMS(b); i++)
        {
                float width = Min(GIDX_GET_MAX(a, i), GIDX_GET_MAX(b, i)) - Max(GIDX_GET_MIN(a, i), GIDX_GET_MIN(b, i));
                if (width < 0.0)
                        return 0.0;
                /* Multiply by minimal length of remaining dimensions. */
                result *= width;
        }
        POSTGIS_DEBUGF(5, "volume( %s intersection %s ) = %.12g", gidx_to_string(a), gidx_to_string(b), result);
        return result;
}

References gidx_dimensionality_check(), gidx_is_unknown(), and result.

Referenced by gserialized_gist_picksplit_constructsplit().

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