It gives you a lot of expressive convenience, you can write the programs much more cleanly, but most importantly, it's fast.
你可以把一些程序写的更清楚,最重要的是,它的效率非常高。
where they are no longer efficiently working for their company.
他们工作的效率就不再那么高了。
And in practical terms, we can define the efficiency as the ratio of the heat in to the work out.
在实际中,我们定义,效率为热与功的比值。
Now, we concluded last week at looking at sorts and efficiency, some new notation called asymptotic notation and we'll continue that story today.
上周我们着眼于排序和效率问题,并提出一些渐近线的新符号,今天我们将继续讨论相关内容。
Now. It's a quick sidebar, I've got to say, I'm sure talking about efficiency to folks like you probably seems really strange.
这是个快速寻找的工具,我必须说跟你们讨论效率,看起来有点奇怪。
Whether they're more inefficient when things are going up or when things are going down.
是不是在事情进展顺利或受阻的时候,市场会更没有效率。
If the vehicle in the unfortunate circumstances of a collision, has to be able to maintain the security of the hydrogen which means more mass, which means a lot of the efficiency is being squandered What's the environmental impact of hydrogen production?
如果车辆,在碰撞中发生了不幸,要仍然能够保持氢气的安全性的话,意味着需要更多的质量,也就是说大部分效率被浪费了,制氢对环境有什么影响呢?
People do that with differing levels of efficiency.
人们存储能量的效率各不相同
And he talks to me about my productivity.
他还跟我谈了我的工作效率。
I mean, isn't it somewhat inefficient to load it really deep, because I assume if a spear is only six feet long, what are people in the back going to be doing?
我觉得,过于厚实的方阵会影响效率,据我所知,长矛也就六尺来长,那站在方阵后方的战士都在干什么呢
He's going to ameliorate their conditions, he's going to make their slavery on his plantations so effective, so good, such a even joyous form of labor, that he will be doing God's work by improving slavery.
他会改善奴隶们的生活条件,他会让自己种植园的奴隶们,提高工作效率,优化管理模式,奴隶甚至是一种令人享受的工作,他会按照上帝的旨意提升奴隶的生活水平
In principle, this value, this efficiency, can approach 1 as the low temperature approaches absolute zero.
这个值,效率,当低温热源的温度1,是据对零度时可以达到一。
And so instead of defining efficiency the way you've got it written there, I'm going to define what's called something different for a refrigerator which is called the coefficient of performance.
现在我们不用,效率的那个定义,我给出一个,有关制冷机的,新的定义,叫做制冷系数。
Is this possible? That's what the first law says it's possible; work is heat, and heat is work, and they're the same thing. You can break even 100% maybe. So let's go back and see what work is.
00%的效率,我们可以从大气中吸收热量,用来驱动我们的汽车,效率也应该能达到。
So what this says is the efficiency of any reversible engine T1 has to be one minus T2 over T1.
这就是说,任何可逆热机的效率都是,负T2除以。
Now that already tells us what we know, which is that the efficiency is going to be something less than zero, right?
我们都知道这个,这结果就是说效率,是负的,对吗?
But what we-- what we do want to do, is to give you some intuition about how to approach questions of efficiency.
但是我们想要你们产生,对于处理效率问题的一些直觉,你应该会意识到为什么。
I want to talk about efficiency, and we're going to, or at least I'm going to, at times also refer to this as orders of growth, for reasons that you'll see over the next few minutes.
为什么是很有价值的,我想要讨论下效率,我们将会,或者至少我将会不时的,提到有序的增长,原因你们很快就会明白的。
And we want to help you learn how to map a problem into a class of algorithms of some efficiency That's our goal.
学会如何将一个问题,映射到一类,提升效率的算法中去,这就是我们的目标。
If you could get to zero degrees Kelvin, you'd get perfect efficiency, 0 but you can't get to zero degrees Kelvin, you can't. Even if you have an infinite amount of resources, you can't get there.
如果能达到,你就能获得完美的效率,但你得不到,得不到,即使你有无穷多的资源,你也做不到。
Alright, I have the problem so clearly this algorithm whatever it's gonna be is gonna be at least twice as fast because I'm doing half as much work.
现在,这个问题已变得清晰,不管怎么样,排序算法的效率,至少是之前的两倍,因为我只需要做一半的工作。
It makes you believe, initially, in the feasibility of perfect efficiency.
你们就会明白,它一开始让你相信完美效率的可行性。
Which is efficiency.
关于效率的内容了。
In that process there is a metabolic engine at work, and some people have an efficient engine so that the calories in get banked in the fat, other people have an inefficient engine, that is the calories get wasted as body heat and things like that, and they tend not to gain weight.
这过程中人体内有个工作着的代谢引擎,有些人的代谢引擎效率很高,热量便转化为脂肪储存起来,另一些人的效率低下,能量就以体温等形式被浪费了,因此他们就不容易发胖
That in many cases, I can gain efficiency if I'm willing to give up space. Having said that though, there may still be a problem, or there ought to be a problem that may be bugging you slightly, which is how do I guarantee that my hash function takes any input into exactly one spot in the storage space?
普遍存在的增益和权衡,在许多的例子中,可以通过牺牲空间而得到效率方面的增加,话说回来,仍然存在一个问题,或者应该会有一个问题困扰着你,就是我如何保证我的哈希函数能够准确将,任一输入映射到相应的唯一的存贮空间中去?
The efficiency for the one on the left q1 is minus w over q1, The efficiency prime for the one on the right is minus w prime over q1 prime.
左边的效率是,负w除以,右边的效率是,负w一撇除以q1一撇。
Some programs won't stop until you're old and gray. And these are really different efficiencies, and we want to give you a sense of how do you reason about those different kinds of programs.
头发花白之前是不会停的,这些是因为它们的效率不同,我们想要给你们理解,这些程序之所以,表现不同的原因。
All right, so you can't get perfect efficiency, 0 but at least if you were able to go to zero degrees Kelvin, then you'd be all set.
好吧,你得不到完美的效率,但至少如果能把温度降到,那你就万事俱备了。
I mean, lately they've been more inefficient, in my view, because the Fed's creating too much money.
我是说,最近市场表现的更没效率,在我看来,这是因为美联储发行了太多的货币。
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