gidx_union_volume()

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

static

Definition at line 246 of file gserialized_gist_nd.c.

{
        float result;
        int i;
        int ndims_a, ndims_b;
 
        POSTGIS_DEBUG(5, "entered function");
 
        if (!a && !b)
        {
                elog(ERROR, "gidx_union_volume received two null arguments");
                return 0.0;
        }
 
        if (!a || gidx_is_unknown(a))
                return gidx_volume(b);
 
        if (!b || gidx_is_unknown(b))
                return gidx_volume(a);
 
        if (gidx_is_unknown(a) && gidx_is_unknown(b))
                return 0.0;
 
        /* Ensure 'a' has the most dimensions. */
        gidx_dimensionality_check(&a, &b);
 
        ndims_a = GIDX_NDIMS(a);
        ndims_b = GIDX_NDIMS(b);
 
        /* Initialize with maximal length of first dimension. */
        result = Max(GIDX_GET_MAX(a, 0), GIDX_GET_MAX(b, 0)) - Min(GIDX_GET_MIN(a, 0), GIDX_GET_MIN(b, 0));
 
        /* Multiply by maximal length of remaining dimensions. */
        for (i = 1; i < ndims_b; i++)
                result *= (Max(GIDX_GET_MAX(a, i), GIDX_GET_MAX(b, i)) - Min(GIDX_GET_MIN(a, i), GIDX_GET_MIN(b, i)));
 
        /* Add in dimensions of higher dimensional box. */
        for (i = ndims_b; i < ndims_a; i++)
                result *= (GIDX_GET_MAX(a, i) - GIDX_GET_MIN(a, i));
 
        POSTGIS_DEBUGF(5, "volume( %s union %s ) = %.12g", gidx_to_string(a), gidx_to_string(b), result);
 
        return result;
}

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

Referenced by gserialized_gist_penalty().

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