gidx_inter_volume()

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

static

Definition at line 365 of file gserialized_gist_nd.c.

References gidx_dimensionality_check(), and gidx_is_unknown().

Referenced by gserialized_gist_picksplit_constructsplit().

{
        int i;
        float result;

        POSTGIS_DEBUG(5,"entered function");

        if ( a == NULL || b == NULL )
        {
                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;
}

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