为什么要说F是一个梯度场？
Now it should be a gradient field.
那么它应该就是一个梯度场。
也就是梯度场。
Say that it is a gradient field.
如果F是梯度场。
So, indeed, this is not a gradient field.
因此这不是一个梯度场。
添加一个渐变。
它不是梯度。
Yes? How do I know the direction of a gradient?
我怎样知道梯度的方向？
This background has a gradient applied to it.
背景应用有渐变。
The problem is not every vector field is a gradient.
问题是，不是所有向量场都是梯度。
It is a gradient field. We need three conditions.
这是一个有势场，我们需要三个条件。
So how do we get a gradient background on a shell?
那么如何在shell上得到渐变的背景色呢？
The question is for which value of a is this a gradient?
问题是a取多少时，这是一个梯度场？
We have said if we have a gradient field then we have this.
如果有一个梯度场，那就能得到这个。
If you have a gradient field then it should have this property.
如果给定一个梯度场，那么它就应该满足这个性质。
You know it's a gradient, f and you know the function, little f.
如果知道一个梯度，相应地就有一个函数。
Yes? How do you determine whether something is a gradient or not?
怎样确定一个场是不是梯度？
So, if you have a gradient field, it's what's called conservative.
如果有一个梯度场，它也是一个保守场。
And that means also it's a gradient field. It's the same thing.
这意味着，F是个梯度场，这是一样的。
An image is used in the background to provide a gradient to white.
在背景中使用一个图像提供到白色的逐变。
Check the Bending Options to apply an Inner Shadow and a Gradient Overlay.
确保混合选项中应用了内阴影和渐变叠加。
So, in particular, only if you have a conservative field, a gradient field.
特别地，仅当是保守场，即有势场时才可以使用。
One is to say that the vector field is a gradient in a certain region of a plane.
一个是向量场,在给定平面区域内是梯度场。
The question is for which value of a is this going to be possibly a gradient?
问题是a为多少时,这才可能是个梯度场？
The main difference is the addition of a gradient to give it a fresher aesthetic.
主要变化是增加了色彩渐变，使得视觉上更加美观。
And, of course, it is not a coincidence because this vector field is a gradient field.
当然这并非巧合，因为这个向量场是有势场。
It changes things quite a bit, however, when it comes to testing whether a field is a gradient field.
然而，当考虑到一个场是否是一个有势场时，它有极大的影响。
If we have a vector field that cannot possibly be a gradient then we shouldn't try to look for a potential.
如果一个向量场不可能是梯度场，那我们就不应该尝试去找势函数。
This style is set to reflect the heading five pixels below it, with a gradient effect applied to the reflection.
设置这个样式以在标题下方5个像素处反射标题，并对倒影应用一个渐变效果。
And it is a gradient field in that part of the plane and conservative and so on. The answer for now is, in general, no.
在那部分平面上，梯度场，是保守的，目前来说结论一般是不对的。
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