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回，是在某深夜，他们将它带到了间议室，连接上彩色投影电视试。

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 点积是个非常有用几何工具用于理解投影和试向量是否指向同个方向。