Function dot

crawl-ref/source/perlin.cc:120–123

    }

    static double dot(Grad g, double x, double y)
    {
        return g.x*x + g.y*y;
    }
    static double dot(Grad g, double x, double y, double z)
    {
        return g.x*x + g.y*y + g.z*z;