If x is high relative to x-bar--this is positive-- then y tends to be low relative to its mean y-bar and this is negative.

如果x比x均值要大,这个为正,而y比y均值小,这个为负

耶鲁公开课 - 金融市场课程节选

Y I'm not passing an x and I'm not passing a Y, &y I'm passing an ampersand x and ampersand y and can you take a guess as to what the ampersand operator must mean?

我不是传递X，也不是传递，我传递的是&x和,你们可以猜一猜,这个&符号是什么意思？

哈佛公开课 - 计算机科学课程节选