This will result in PHP reporting a warning every time an uninitialized variable is used, each bad file access, and other (mostly) harmless errors, but might also represent a potential attack vector.
So, actually on Tuesday we'll see how to decide whether a vector field is a gradient or not, and if it is a gradient, how to find the potential function.
周二我们就知道,怎样确定一个场是不是梯度,如果确实是梯度的话,怎样算出势函数。
3
I want to find the potential for this vector field.