|
h********d
发帖数: 381 | 2 呵呵，欢迎tangent回归，真是虚荣，看到有人给你打招呼，就赶忙出来漏个脸，呼唤 |
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a******g
发帖数: 13519 | 3 【 以下文字转载自 Military 讨论区 】
发信人: alexsung (Keep your feet on the ground.), 信区: Military
标 题: 题目越短越难！谁能证明Tangent 1°是有理数吗？
发信站: BBS 未名空间站 (Tue Feb 13 17:03:07 2018, 美东)
tan1°是有理数吗？
10个字，引出了日本高考史上最短的问题
据传，当年学生们有如下答案：
×无理数に决まってんじゃん（30％） 显然是无理数嘛。（30%的学生如此回答）
×なんとなく无理数じゃん？ ほら、何というか・・・（20％）
我觉得是无理数吧？你看，怎么说呢……（20%）
×sin1°が无理数で、cos1°も无理数だから、tan1°= sin1°/ cos1°も无理数。(
20％)
因为sin1°和cos1°都是无理数所以tan1°也是无理数。（20%）
×で、sin1ﾟ, cos1ﾟはなぜ无理数かというと、πが无理数なのは自明
だから、sin1ﾟ, cos1ʎ... 阅读全帖 |
|
t*******r
发帖数: 22634 | 4 俺再解释一下 proof path 里不出现 transcendental expression
的意思。。。比如就算某个角度本身是 transcendental expression，
但是因为是求证角度相等，所以实际没有真正去算那个角度，而是计算该
角度的 tangent，比较后证明其 tangent 相等。。。所以严格
的说，proof path 里没有出现那个角度本身，只出现了那个角度
的 tangent。。。如果求那个 tangent不出现 transcendental
expression 的话，那么这个 proof path 里就没有出现 transcendental
expression。。。是这个意思。。。俺本着以防误解的精神，今天实在是
比较唐。。。 |
|
t*******r
发帖数: 22634 | 5 俺发现万恶的老师，是如何设计那道玩弄大伙儿的几何证明题的。
其实很简单，一般的等角证明题，出现在 algebraic proof path
里的，是角度本身，然后角度加加减减，罗罗嗦嗦一通，证明相等
。。。
而前面那道等角证明题，老师玩弄了一下大伙儿的感情的是，那题
出现在 algebraic proof path 里的，不是角度本身，而是角度的
tangent。。。结果一杆子打翻一船人。。。
其实在俺的前面有关 algebraic vs transcendental 的探讨之后，
这种破题一秒钟就能看出来。。。俺解释如下：
首先，如果在 algebraic proof path 里只能通过角度的
tangent 的而不是角度本身的，那在该角度形成的过程中，
必然是通过一个（或多个）长度的 expression （指跟“参数”
相关）而形成的。
其次，初中老师您总不能在 proof path 里，把角度加加减减，
和 tangent 的加加减减，同时出现吧。。。初中老师您如果这么
干，您有种，您这题 proof path 里铁定出现 transcendental
expression，... 阅读全帖 |
|
t*******r
发帖数: 22634 | 6 俺再解释一下 proof path 里不出现 transcendental expression
的意思。。。比如就算某个角度本身是 transcendental expression，
但是因为是求证角度相等，所以实际没有真正去算那个角度，而是计算该
角度的 tangent，比较后证明其 tangent 相等。。。所以严格
的说，proof path 里没有出现那个角度本身，只出现了那个角度
的 tangent。。。如果求那个 tangent不出现 transcendental
expression 的话，那么这个 proof path 里就没有出现 transcendental
expression。。。是这个意思。。。俺本着以防误解的精神，今天实在是
比较唐。。。 |
|
t*******r
发帖数: 22634 | 7 俺发现万恶的老师，是如何设计那道玩弄大伙儿的几何证明题的。
其实很简单，一般的等角证明题，出现在 algebraic proof path
里的，是角度本身，然后角度加加减减，罗罗嗦嗦一通，证明相等
。。。
而前面那道等角证明题，老师玩弄了一下大伙儿的感情的是，那题
出现在 algebraic proof path 里的，不是角度本身，而是角度的
tangent。。。结果一杆子打翻一船人。。。
其实在俺的前面有关 algebraic vs transcendental 的探讨之后，
这种破题一秒钟就能看出来。。。俺解释如下：
首先，如果在 algebraic proof path 里只能通过角度的
tangent 的而不是角度本身的，那在该角度形成的过程中，
必然是通过一个（或多个）长度的 expression （指跟“参数”
相关）而形成的。
其次，初中老师您总不能在 proof path 里，把角度加加减减，
和 tangent 的加加减减，同时出现吧。。。初中老师您如果这么
干，您有种，您这题 proof path 里铁定出现 transcendental
expression，... 阅读全帖 |
|
l***h
发帖数: 9308 | 8 我记得以前给过一个术语链接在某个置项贴里面，可能归档了吧，再贴一下，新人不懂
的可以参考一下
http://www.runnersworld.com/community/forums/runner-communities
Your friendly beginning runner's guide to .... runner's jargon.
You'll notice we don't have a FAQ here -- that's because we want you to ask
your questions, join in, become part of the community! That said, I am sure
new runners get overwhelmed by phrases we throw around all the time here
with impunity; you probably think we're all speaking some strange language.
To follow along here, ... 阅读全帖 |
|
W***i
发帖数: 833 | 9 算了，我还是再贴一遍，
Your friendly beginning runner's guide to .... runner's jargon.
You'll notice we don't have a FAQ here -- that's because we want you to ask
your questions, join in, become part of the community! That said, I am sure
new runners get overwhelmed by phrases we throw around all the time here wit
h impunity; you probably think we're all speaking some strange language. To
follow along here, it's really helpful just to know some general stuff and w
hat terms mean. So in the interest of hel... 阅读全帖 |
|
l***h
发帖数: 9308 | 10 marathon pace
跑步黑话大全
Your friendly beginning runner's guide to .... runner's jargon. Cool
You'll notice we don't have a FAQ here -- that's because we want you to ask
your questions, join in, become part of the community! That said, I am sure
new runners get overwhelmed by phrases we throw around all the time here wit
h impunity; you probably think we're all speaking some strange language. To
follow along here, it's really helpful just to know some general stuff and w
hat terms mean. So in the in... 阅读全帖 |
|
x********u
发帖数: 12 | 11 关于近期Fano流形上构造Kähler-Einstein度量的工作
最近公布的Fano流形上构造Kähler-Einstein度量的工作，是Kähler几
何近年来引人注目的进展，专家们正在验证。若验查无误，将证明丘成桐关于Fano流形
的构想与猜测是正确的。Donaldson的稳定性条件是其中的关键步骤，还需在代数几何
上把此概念搞清楚，这样丘猜测就为深刻理解Fano流形奠定了基础。由于近期发生了一
些混淆不清的事件，我们将相关工作的公开记录做了客观、学术的分析，望有助于澄清
事实。本文主要涉及文献的比较，阅读本文无需是专家，数学专业本科高年级学生或研
究生可读懂绝大部分。欢迎关于数学上的批评与指正。
本文分三个部分：
1) 陈-Donaldson-孙的报告与文章
2) 田的报告与文章
3) 结论
I. 陈-Donaldson-孙的报告与文章
在最近的一系列文章中，陈秀雄-Donaldson-孙崧（CDS）宣布解决了Kähler
几何中悬置多年的问题。
丘成桐猜测：设M为一紧致K... 阅读全帖 |
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a*********3
发帖数: 660 | 12 定义 definition变量 variable面积 area直径 diameter半径 radius公式 formula
单价 unit price范围 range/scope/extent集合 set法则 principle本金 principal利
率 interest rate利息 interest单利 simple interest复利 compound interest正数
positive number负数 negative number解析式 analytic expression分类讨论
classified discussion性质 nature （不是很确定）奇函数 odd function偶函数
even function对称 symmetric坐标原点 origin单调性 monotonicity（不是很确定）
任意 random周期性 periodic 有界性 boundedness 数学 mathematics, maths(BrE)
, math(AmE) 公理 axiom 定理 theorem 计算 calculation 运算 operat... 阅读全帖 |
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g****a
发帖数: 1520 | 13 【 以下文字转载自 WaterWorld 讨论区 】
发信人: xiaoshushu (songshu), 信区: WaterWorld
标 题: 关于近期Fano流形上构造KE度量的工作(转载)
发信站: BBS 未名空间站 (Sat Aug 31 10:30:12 2013, 美东)
关于近期Fano流形上构造Kähler-Einstein度量的工作
最近公布的Fano流形上构造Kähler-Einstein度量的工作，是Kähler几
何近年来引人注目的进展，专家们正在验证。若验查无误，将证明丘成桐关于Fano流形
的构想与猜测是正确的。Donaldson的稳定性条件是其中的关键步骤，还需在代数几何
上把此概念搞清楚，这样丘猜测就为深刻理解Fano流形奠定了基础。由于近期发生了一
些混淆不清的事件，我们将相关工作的公开记录做了客观、学术的分析，望有助于澄清
事实。本文主要涉及文献的比较，阅读本文无需是专家，数学专业本科高年级学生或研
究生可读懂绝大部分。欢迎关于数学上的批评与指正。
本文分三个部分：
1) 陈-Don... 阅读全帖 |
|
g****a
发帖数: 1520 | 14 【 以下文字转载自 WaterWorld 讨论区 】
发信人: xiaoshushu (songshu), 信区: WaterWorld
标 题: 关于近期Fano流形上构造KE度量的工作(转载)
发信站: BBS 未名空间站 (Sat Aug 31 10:30:12 2013, 美东)
关于近期Fano流形上构造Kähler-Einstein度量的工作
最近公布的Fano流形上构造Kähler-Einstein度量的工作，是Kähler几
何近年来引人注目的进展，专家们正在验证。若验查无误，将证明丘成桐关于Fano流形
的构想与猜测是正确的。Donaldson的稳定性条件是其中的关键步骤，还需在代数几何
上把此概念搞清楚，这样丘猜测就为深刻理解Fano流形奠定了基础。由于近期发生了一
些混淆不清的事件，我们将相关工作的公开记录做了客观、学术的分析，望有助于澄清
事实。本文主要涉及文献的比较，阅读本文无需是专家，数学专业本科高年级学生或研
究生可读懂绝大部分。欢迎关于数学上的批评与指正。
本文分三个部分：
1) 陈-Don... 阅读全帖 |
|
t******n
发帖数: 6242 | 15 今天无聊，看到这篇无聊的文章，就给你无聊地翻译成英文吧。
探索星系的捷径
A Shortcut to Galaxy Exploration
1. 问苍天情为何物？
1. Ask what love is heaven?
有人类的历史以来，人类就不断地探索自然，扩展了解自然的疆界。哥伦布发现新大陆
就是最好的例子。人类探索自然的勇气是从哪儿来的呢？来自人类情感的力量。那么，
情感是什么东西呢？这是千万年来，文学家探索的主题。在有一些文学家的眼中，物理
学家是没有情感的冷血动物。我就是一个物理学家。但是，我一点也不埋怨这些文学家
。虽然物理学家在自然界的探索中做出了伟大的贡献，但是，物理学家从来就没有给出
情感的物理定义是什么，也没有找到自然界蕴含情感的丝毫证据。所以，虽然人类知道
自己的生存发展跟自然环境是密不可分的，但是，很少有人类表达出对自然环境感谢的
情感。在很多人的眼中，自然界是死亡无情的物质世界。中国有一句古语，叫做“天若
有情天亦老”。因为几乎所有人类相信天是不老的，所以，认为苍天是没有情感的，就
不足为奇了。我提出了一个宇宙生长衰老的模型。虽然这个模型及其简单，能解释大多
... 阅读全帖 |
|
t*******r
发帖数: 22634 | 16 为了避免歧义，俺把俺的 cynical talking 用不严格的
大名词写一下：
我前面说的那个：“解析几何 + Algebra I + 已知斜率->
求笛卡尔坐标系旋转矩阵->求相对斜率”，实际的意思是：
For the similar geometric problems can be solved exclusively
using Euclidean Geometry taught in the average middle school
classrooms, such problems should be able to solve (in a routine
way) by:
1) Using the analytic geometry that limited to algebraic
expressions. (Transcendental constants are allowed, for sure.)
2) Writing algebraic equations for the shapes. Such equations
may contains "addi... 阅读全帖 |
|
t*******r
发帖数: 22634 | 17 为了避免歧义，俺把俺的 cynical talking 用不严格的
大名词写一下：
我前面说的那个：“解析几何 + Algebra I + 已知斜率->
求笛卡尔坐标系旋转矩阵->求相对斜率”，实际的意思是：
For the similar geometric problems can be solved exclusively
using Euclidean Geometry taught in the average middle school
classrooms, such problems should be able to solve (in a routine
way) by:
1) Using the analytic geometry that limited to algebraic
expressions. (Transcendental constants are allowed, for sure.)
2) Writing algebraic equations for the shapes. Such equations
may contains "addi... 阅读全帖 |
|
B******1
发帖数: 9094 | 18 All problems contain the premise that the conditions given are correct. It
is not the student's job to question the validity of the problem. Rather, a
student simply takes what is given and figures out the answer to the problem.
In the present case, since the big circle and the small circle are tangent
to each other, those three points you mentioned HAVE to be on the same line.
Period.
If you want the proof that the 7 cirlces exist, you look no further than
looking at the possibility of draw... 阅读全帖 |
|
c*******v
发帖数: 2599 | 19 从下面的话看来，格林厄姆对股市的波动升降，以及个股的波动升降显然非常熟悉，并
且拥有极其丰富的经验。
总结出来价值投资，看来是因为觉得更profitable。
而不是人家不懂技术分析。
There are two elements of basic importance, I think, that the analyst should
recognize in the behavior of stocks over the last six years. The first is
the principle of continuity, and the other is what I would call the
principle of deceptive selectivity in the stock market.
First, with regard to continuity: The extraordinary thing about the
securities market, if you judge it over a long period of years, ... 阅读全帖 |
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|
a*********a
发帖数: 3656 | 21 then the formula I gave should be it. if you don't require crossing the
points, then it is a different matter.
starting from 0th, you can pick an arbitrary tangent. you have now y0, y0'.
then going to the 1st point, the only thing you can do is a quadratic form.
3 equations for 3 unknowns like I laid out before. y0=a x0^2+b x0+c,y1=a x1^
2+b x1+c,y0'=2 a1 x0+b1)
This will fix the tangent at point 1. then you solve anther equation set of
3. (y1=a x1^2+b x1+c,y2=a x2^2+b x2+c,y1'=2 a1 x1+b1). lath... 阅读全帖 |
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b*******n
发帖数: 51 | 22 Isn't it the tangent point on the tangent line of the hyperbola going cross
the point of risk free portfolio? |
|
z**h
发帖数: 224 | 23 来自主题: Macromolecules版 - 推荐几篇文章 xixi, i am right, i like it.
"The frequency independence of the loss tangent provides the most reliable and
generally valid rheological method to determine gelation."
tangent=G'/G" |
|
w****a
发帖数: 4 | 24 Let C be a curve in the plane, i.e. C is the image of a smooth (= infinitely
differentiable) function f:[0,1]---R^2. Let T be the tangent line to C at
the point f(t0)=(x0,y0). Prove carefully that an affine transformation A
takes A(T) to the tangent line of A(C)=A(f([0,1])) at A(x0,y0). |
|
R********n
发帖数: 519 | 25 考虑一个d-dimensional的黎曼manifold M嵌入在一个D-dimensional的欧式空间里面，
在给定的一点p，我想观察manifold的curvature。
我一个很初等的理解是，是不是可以在点p的tangent space里面取一组基，然后看
manifold在这组基中的每一个basis上弯曲的情况？这样我就能得到d个sclar
curvature。
这个和Ricci curvature有什么关系呢？
我理解的Ricci是，也是要取tangent space的一组基e_i，然后对任意的v,mapping v到
\sum_{i} R(e_i,v)e_i,其中R(e_i,v)是Riemannian curvature tensor
谢谢:-) |
|
J*******3
发帖数: 1651 | 26 http://www.ratemyprofessors.com/ShowRatings.jsp?tid=1484264
Tzuong-Tsieng Moh
Photo Unavailable
School: Purdue University - West Lafayette
Location: West Lafayette, IN
Department: Mathematics
Date
Class
Rating
Comment
4/17/13
MA265
Poor Quality
Easiness1
Helpfulness1
Clarity1
Rater Interest1
Grade ReceivedN/A
I learnt nothing in his lectures. Enough said!
Report this rating
12/10/12
MA265
Poor Quality
Easiness1
Helpfulness1
Clarity1
Rater Interest4
Grade ReceivedN/A
Without a doubt t... 阅读全帖 |
|
J*******3
发帖数: 1651 | 27 http://www.ratemyprofessors.com/ShowRatings.jsp?tid=1484264
Tzuong-Tsieng Moh
Photo Unavailable
School: Purdue University - West Lafayette
Location: West Lafayette, IN
Department: Mathematics
Date
Class
Rating
Comment
4/17/13
MA265
Poor Quality
Easiness1
Helpfulness1
Clarity1
Rater Interest1
Grade ReceivedN/A
I learnt nothing in his lectures. Enough said!
Report this rating
12/10/12
MA265
Poor Quality
Easiness1
Helpfulness1
Clarity1
Rater Interest4
Grade ReceivedN/A
Without a doubt t... 阅读全帖 |
|
Z**********g
发帖数: 662 | 28 能把课教到这个程度，也是奇葩了。
70多岁的人了，艺术照片满天飞，喜欢盯着人眼睛看，同性恋腔调，这大概就是莫宗坚
的风流韵事了。
一个莫宗坚，一个牛满江，都是那个时代坑蒙拐骗的两个典型，老中要引以为戒。
Tzuong-Tsieng Moh
http://www.ratemyprofessors.com/ShowRatings.jsp?tid=1484264
School: Purdue University - West Lafayette
Department: Mathematics
Rate:
1.1 Overall Quality
1.1 Helpfulness
1.1 Clarity
1.4 Easiness
4/17/13
MA265
Poor Quality
Easiness1
Helpfulness1
Clarity1
Rater Interest1
I learnt nothing in his lectures. Enough said!
Report this rating
12/10/12
MA265
Poor Quality
E... 阅读全帖 |
|
|
|
S***p
发帖数: 19902 | 31 Ricci curvature 当做场，量子化之后的，因为还有规范自由度，所以也是规范玻色子
这个规范自由度，gauge freedom?，我觉得从数学的角度很好理解一些，因为tangent
bundle 也是一种vector bundle（可以理解为定义在流行上的张量场）, 也可以定义
gauge transform（数学概念）,
Ricci curvature 从是tangent bundle来的张量场。 |
|
e*******n
发帖数: 4912 | 32 101. 1917年，日本数学家挂谷宗一（Kakeya，S(1886-1947)）提出
一个问题：一位武士上厕所时遭到袭击，他只有一根短棒，为了
挡住射击，短棒应旋转360度（支点可以变化），但厕所很小，
问短棒最少要扫过多大面积？
这个问题引起当时很多人的兴趣，如1925年Birkhoff在他
写的The origin, nature, and influence of relativity
一书中提到“近几年日本数学家挂谷宗一提出的问题，是同样令
人感兴趣的问题”
1928年，苏联数学家Besicovitch，Abram Samoilovitch
（1891-1970）解决了这个问题，答案是可以任意小，1960s
Besicovitch在美国数学会就挂谷问题专门做了期科普电影，
有意思的是中间他打了个喷嚏，Besicovitch觉得很不雅，
坚持要求在录像中把这个镜头剪掉，于是现在人们看到的是
镜头突然转向一边，然后是一声闷响....
102. William James seemed to have what seemed vitally important
ideas in d... 阅读全帖 |
|
D**u
发帖数: 204 | 33 Let me fill the gap to prove "A sphere with 2 points removed can be
partitioned with disjoint circles", and hope it will help.
One a sphere, let the 2 removed points be A and B.
(1) If A and B are opposite to each other (like north pole and south pole),
then the remaining sphere can be partitioned with circles that are
perpendicular to line AB.
(2) If A and B are not opposite to each other, let P_1 be the tangent plane
(to the sphere) at point A, and P_2 be the tangent plane at point B. Assume
P |
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j*******a
发帖数: 101 | 34 一个股票有jump，一个没有，有jump的valotilty大，所有option的价格高，这个好理
解。
有的书用hedge来解释这个：Suppose we short a call option of price C(S_0, 0) (
the black-scholes option price with no jumps) and hold dC/ds units of stocks
. If a jump does not happen, the hedge works perfectly. The call option
price is a convex function. If we graph the option price as a function of
spot for any time t, any tangent of the graph will lie blow. When a jump
happens, we will move instantly along this tangent line, and hence finish at
a point... 阅读全帖 |
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s**e
发帖数: 103 | 35 a more complicated example:
take a set of points x_i (i=0,1,2,3 ......) = -100^{i}
(x0=-1,x1=-100,x2=-10000 ....)
f(x)=sum_{i=0}^{infinite} \tanh(a_i*(x-x_i))/(x_i)
where we use hyperbolic tangent. it is covergent because it is controlled
by 1/x_i which is a geometrical series.
the derivative at any x_i will be dominated by one term tanh(a_i(x-x_i))
because of the property of hyperbolic tangent.
now, d(tanh(a_i(x-x_i)))/dx (x=x_i) = 4*a_i
if we take a_i=x_i, df/dx|_{x=x_i} = 4 which is not go |
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b********t
发帖数: 992 | 36 the whole movie is about tangient univese, which is described in the book "the
philosphy of time travel"
"The Tangent Universe
The Primary Universe is fraught with great peril. War, plague, famine and
natural disaster are common. Death comes to us all.
The Fourth Dimension of Time is a stable construct, though it is not
impenetrable.
Incidents when the fabric of the fourth dimension becomes corrupted are
incredibly rare.
If a Tangent Universe occurs, it will be highly unstable, sustaining itself |
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h*********n
发帖数: 11319 | 37 你说说是多远？
问题给你简化一下：两块石头到底多大？
case 1如果石头长1m，那么登月舱的距离是石头的10倍，
case2 如果石头长20厘米，那么登月舱的距离是石头的50倍，登月舱/相机/地面的夹角
是case1 的1/5
10倍和50倍，考考你，一个平面角在空间里投影到另一个平面上，怎么算？
tangent完全可以差出一个数量级
你y的中学立体几何都怎么学的？
常， |
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u***r
发帖数: 4825 | 38 http://www.economist.com/node/18682839
May 12th 2011 | BEIJING AND ISLAMABAD | from the print edition
PAKISTAN’S ambassador to Beijing, Masood Kahn, was this week fully armed
with metaphors to describe the robust friendship between the two countries.
“We say it is higher than the mountains, deeper than the oceans, stronger
than steel, dearer than eyesight, sweeter than honey, and so on.”
The relationship is indeed a geopolitical keystone for both countries.
Pakistan serves as China’s closest fri... 阅读全帖 |
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z****g
发帖数: 3340 | 39 Vikram Pandit, who steered Citigroup through the 2008 financial crisis and
the choppy years that followed, abruptly left the bank Tuesday, stepping
down as chief executive and as a director.
The move shocked Wall Street, and Citigroup offered no explanation. There
had been no hint of the departure Monday, when the bank discussed its strong
third-quarter earnings in lengthy calls with financial analysts and
reporters.
A second top executive resigned as part of the shake-up: president and chief
op... 阅读全帖 |
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o*******n
发帖数: 407 | 40 他这说的是100米升6米
就是tangent=6/100
atan(6/100)*180/pi=3.433 degree
3.4度啦，不是6.1度 |
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X******i
发帖数: 1384 | 41 谢谢，我没干过数值计算的活，这次是赶鸭子上架。我大学是在法国读的，所以有些中
文术语不清楚，牛顿迭代是不是就是newton raphson?收敛应该是converge吧？
我的问题有点复杂，前面没有解释清楚。关键是逼近值一定要准，因为这只是一个单元
里的逼近值，然后输出到下一个单元作为输入。一共有几千个单元，所以如果不准的话
最后的误差会被放大。我最开始用的是brute forcing,一步一步向交点逼近，计算停止
在误差小于0.1%（举例），但是如果我的step取的不够小的话，可能最靠近交点的逼近
值都不能在0.1%以内，无法converge。但是step取的小的话，计算量又很大。
bisection我也用过，也不准尤其是在多个单元之后，误差会越来越大。
我还试过shooting method,其实差不多就是newton raphson了，两边取tangent line向
中间逼近，但是他的缺点是逼近点在不同的单元里有时在左侧，有时在右侧，不过倒是
有可能互相取消。但是横坐标的数值不是整数，给我后面的运算带来很多麻烦。 |
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m**********e
发帖数: 12525 | 42 关键这段:
Lorentzian流形因为时间分量是虚数,所以流形的切矢量数学上可以分为类时,类空,和
null三类:
参见causal strecture:
.... Unlike Riemannian manifolds with positive-definite metrics, a signature
of (p, 1) allows tangent vectors to be classified into timelike, null
or spacelike (see Causal structure)....
https://en.wikipedia.org/wiki/Causal_structure |
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m**c
发帖数: 7349 | 43 Now he is the president-elect. His first act was to give an unusually
measured speech in which he promised reconciliation at home, and said that
“we will get along with all other nations willing to get along with us.”
As he assembles his administration, he needs to know that the world has
already taken a lot of what he has said as terrifying promises. Which Donald
Trump will take office in January?
The one who continually went off on reckless and damaging tangents during
campaign speeches? Or th... 阅读全帖 |
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M******a
发帖数: 6723 | 44 【 以下文字转载自 Mod_CHN_Hist 讨论区 】
发信人: Mayingba (吳鐘學), 信区: Mod_CHN_Hist
标 题: 奉天兵工厂
发信站: BBS 未名空间站 (Sun Jan 28 20:29:57 2018, 美东)
https://wwiiafterwwii.wordpress.com/2017/04/03/mukden-arsenal-after-wwii/
Mukden Arsenal after WWII
April 3, 2017 jwh19752 Comments
(Zhang's Gate, the old entrance to Mukden Arsenal)
For people interested in Japanese firearms of WWII, the name Mukden Arsenal
is familiar. The history of the facility after Japan's defeat is less well
known. Under various names, it did surv... 阅读全帖 |
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q******s
发帖数: 7469 | 45 还要什么技术，切入角度，算tangent这么麻烦，直接鸡吧长长点就好了。
: 用得着“纳米涂料”这么费劲么？
: 其实，只要掌握好尿流的切入角，就可以避免回溅了。这难道不是负责男人基本
功么？
|
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D**S
发帖数: 24887 | 46 鸡巴长，你直接90度入射，照样给你溅回来。
另：那不叫tangent,叫incident,OK? |
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s******r
发帖数: 5309 | 47 Bob Woodward’s new book reveals a ‘nervous breakdown’ of Trump’s
presidency
Bob Woodward’s new book, “Fear: Trump in the White House,” is based on
hundreds of hours of in-depth interviews. (Jabin Botsford/The Washington
Post)
By Philip Rucker and
Robert Costa
September 4 at 11:08 AM
John Dowd was convinced that President Trump would commit perjury if he
talked to special counsel Robert S. Mueller III. So, on Jan. 27, the
president’s then-personal attorney staged a practice session to try to make... 阅读全帖 |
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b***n
发帖数: 1210 | 48 夹角就够了. 记得是tangent角度乘以一个系数. |
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l****z
发帖数: 29846 | 49 April 4, 2012 by TWB
Bigotry, stupidity. Same difference. Lawrence O’Donnell, the guy who took
Olberdouche’s spot on MSNBC, went off on an anti-Mormon, anti-Romney
tangent, which will unfortunately become rather frequent once the general
election campaign heats up. You know, freedom of religion is only good in
the minds of liberals if you’re talking about radical Islam or being a
godless heathen.
Kevin Williamson at The Corner has created a new award for Lawrence O’
Donnell and his ilk. It’s c... 阅读全帖 |
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l****z
发帖数: 29846 | 50 Gun control advocates refuse to properly assess human vulnerability.
by
Jack Dunphy
December 26, 2012 - 12:19 am
On the evening of December 14, when the horror of Sandy Hook Elementary
School was quite rightly the only subject on everyone’s minds and lips, I
was in my car listening to talk radio. I tuned to one station and then
another before choosing Dennis Miller’s program. I was eager to hear Mr.
Miller’s take on the day’s sorrows, but I was astonished to hear him and
his guest (I’ve forgotte... 阅读全帖 |
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