They brought the prototype out only once, late at night, to test it on the color projection television in one of the conference rooms.

这台机器只被他们带出过房间一回，是在某一天，他们将它带到了一间议室，连接上彩色投影行测试。

So to sum up, on the surface, the dot product is a very useful geometric tool for understanding projections and for testing whether or not vectors tend to point in the same direction.

综上所述 在表面上 点积是一个非常有用几何工具用于理解投影和测试向量是否指向同一个方向。