h**********c
发帖数: 4120 | 1 Please, anybody know the Lorenz system's nonzero equilibria
When the manifold is 2d stable, 1d unstable \rho \in (40,100)
I want to know the explicit form of the three eigenvectors of the Jacobians. maybe analytical not numerical.
Or, how to say,
given a polynomial to order of three.
is it possible to get the roots expressed by the coefficients.
or given a matrix (3x3), get the eigenvector expressed as the matrix elements. |
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g***i
发帖数: 90 | 2 I have considered to use Gaussian elimination on the syl matrix.
Say, if the syl matrix is in the form that each row are the
coefficients of the polynomials, then apply GE to the rows.
The last nonzero row has the coefficients of the gcd.
Thus I tried to prove the reduced matrix has nonzero diagonal
entry in the last nonzero row. But I can't find a way to
prove this:( Any idea? |
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n*******l
发帖数: 2911 | 3 Two cases.
1. If t=0 is an eignevalue of AB, then AB is singular and BA is singular too.
Hence t=0 is an eigenvalue of BA.
2. If t is a nonzero eigenvalue of AB, then there is a nonzero eigenvector x
such that ABx=tx and Bx can not be zero (if Bx=0, then ABx=0, but tx is not
zero, contradiction). Thus Bx is a nonzero eigenvector for BA with
eigenvalue t. |
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g****g
发帖数: 1828 | 4 In probability theory, the normal (or Gaussian) distribution, is a
continuous probability distribution that is often used as a first
approximation to describe real-valued random variables that tend to cluster
around a single mean value. The graph of the associated probability density
function is “bell”-shaped, and is known as the Gaussian function or bell
curve:[nb 1]
f(x) = \tfrac{1}{\sqrt{2\pi\sigma^2}}\; e^{ -\frac{(x-\mu)^2}{2\sigma^2}
},
where parameter μ is the mean (location of the pe... 阅读全帖 |
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s*******y
发帖数: 558 | 5 Let us define a function f (x, y) = xy where x and y can be any nonzero
numbers in the real domain R, e.g., f(2, -3.5) = 2 * (-3.5) = -7.
Now assume the value of f(x, y) is fixed, but y can change, can we
say that any nonzero x in R is equally likely to be mapped to f(x,y)?
How to prove that? |
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D**o
发帖数: 2653 | 6 注意作者 \author{YHBKJ}
Atiyah-Bott Localization 1
2012-09-05 09:24:19
\documentclass[a4paper,12pt]{article}
\usepackage{amsfonts}
\usepackage{amsmath,amsthm,amssymb}
\usepackage{CJK,graphicx}
\usepackage{amscd}
\usepackage{amssymb}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{corollary}{Corollary}[section]
\newtheorem{definition}{Definition}[section]
\newtheorem{lemma}{Lemma}[section]
\begin{document}
\title{\textbf{\Huge{Atiyah-Bott Localization 1}}}\author{YHBKJ}\date{}\
maketitle
\begin{ab... 阅读全帖 |
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k*****y
发帖数: 744 | 7 Say the number is [a1, a2, ..., a10],then
1*a1 + 2*a2 + ... + 10*a10 = total number of digits = 10.
Let N be the number of nonzero digits in it. Then
10 = 1*a1 + 2*a2 + ... + 10*a10
>= 1*1 + 2*1 + ... + N*1
= N*(N+1)/2,
Hence N <= 4.
If N=4, that means there are 6 zero's, hence a6=1. But then
1*a1 + 2*a2 + ... + 10*a10
>= 1*1 + 2*1 + 3*1 + 6*1 = 12, contradiction!
If N=3, then a7 = 1. To make the sum equal 10, the number has to be
1100001000, which does not satisfy the condition.
If N=2, t... 阅读全帖 |
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S*********g
发帖数: 5298 | 8 assume t is the vector, following operation gives the result you want
nonzeros(t.*(1-sign(abs(imag(t)))))
***************************************************************
>> t=[1 2 3 4 5+ rand*i]
t =
Columns 1 through 3
1.0000 2.0000 3.0000
Columns 4 through 5
4.0000 5.0000 + 0.9501i
>> nonzeros(t.*(1-sign(abs(imag(t)))))
ans =
1
2
3
4
**************************************************************** |
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s****h
发帖数: 3979 | 9 data frame API 1.3 才有。
弄进一个dense vector很直接：
import org.apache.spark.mllib.linalg.{Vector, Vectors}
val path = "～/test60m.txt"
val minPartitions = 4
val parsed = sc.textFile(path, minPartitions)
.map(_.trim)
.filter(line => !(line.isEmpty || line.startsWith("#")))
val a = parsed.map({ line =>
val fields = line.split(" ")
(fields(0).toInt, fields(1))})
val dataLoad = a.map(x => (x._1, Vectors.dense(x._2.split(',').map(_.
toDouble))))
可是sparse vector就不会了。
不知道怎么结合下面的例子
// Create a dense vector (... 阅读全帖 |
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s*****V
发帖数: 21731 | 10 主流物理学界不能接受的是老子花了200亿搞了加速器也没装出个鸟来，你丫一个车库
里面车出来的东西还能颠覆物理学的基础？
“
Now, the individuals behind this particular "breakthrough" say that they
combine some random ingredients – a church bell, microwaves, a
superconductor, a cherry pie, the U.S. constitution, a witch's gray hair,
and a few others – and they do a certain measurement and obtain a nonzero
force in micronewtons, or something like that, which they can't explain. (
Even if it worked in principle, such forces could be attributed to a
mosquito a... 阅读全帖 |
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a****l
发帖数: 8211 | 11 https://en.wikipedia.org/wiki/0.999...
More generally, every nonzero terminating decimal has two equal
representations (for example, 8.32 and 8.31999...), a property true of all
base representations. |
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c******i
发帖数: 4091 | 12 作者疑似走地鸡屎地粪坑失散多年的米国婊弟
文后的读者反馈也值得一读。
呵呵
http://www.alligator.org/opinion/columns/article_d5d4f286-5dfe-
Loganville woman jumped to the gun
We can learn a lot about the problematic illusion-making tendencies of the
discourse on guns by analyzing a recent news story from Loganville, Ga.
You may have heard about it: A lady was hiding in her attic from a burglar
with her two kids and her Saturday night special when he used a crowbar to
bust in on them. So she did what she had to do. Next thing you kno... 阅读全帖 |
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k**n
发帖数: 482 | 13 the matrix A will be a very sparse block-tridiagonal matrix if you use
simple central difference scheme to discretize the first and second
derivatives of u w.r.t. s and v, there is a function in Matlab called "
spdiags" that can define this matrix efficiently, basically you need to
define all the nonzero entries of matrix A into several vectors and use
those vectors to define A, the index of each row of A corresponds to the
index in the vector u(t) one by one, hope this helps |
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t*******r
发帖数: 22634 | 14 高中数学慢班要求理解有理数指数的证明，还有有理数和无理数加法乘法的问题：
http://www.corestandards.org/Math/Content/HSN/RN/
Extend the properties of exponents to rational exponents.
CCSS.MATH.CONTENT.HSN.RN.A.1
Explain how the definition of the meaning of rational exponents follows from
extending the properties of integer exponents to those values, allowing for
a notation for radicals in terms of rational exponents. For example, we
define 5^(1/3) to be the cube root of 5 because we want (5 ^ (1/3)) ^3 = 5 ^
((
1/3)*3) to hold, so (... 阅读全帖 |
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m*****u
发帖数: 5534 | 15 make $0.3 dollar.
This is the smallest nonzero change in my account. |
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z*******1
发帖数: 1588 | 16 我想这应该比较清楚了，只要拿到1042S，你就填那上边的收入，then line7
就nonzero了，你就可以白拿work credit了。去年我就是根据1042S填的，今年
没收到，下周就去要，你要是不急，等我填了以后告诉你。
reported |
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s******4
发帖数: 1322 | 17 Right, pretty challenging
However he/she would have nonzero chance if applying visa and enter before
filling 130 and 485
★ 发自iPhone App: ChineseWeb 7.7 |
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s******4
发帖数: 1322 | 18 Yes that is why I said nonzero probability
Maybe the VO doesn't care
★ 发自iPhone App: ChineseWeb 7.7 |
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b**l
发帖数: 33123 | 19 以前好像是不能选nonzero deductible的。这是当时我觉得麻省车保唯一的一个好处。
选了
progressive |
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B*****s
发帖数: 3463 | 20 我的dealer 就这么说的，不过我不是geico
以前好像是不能选nonzero deductible的。这是当时我觉得麻省车保唯一的一个好处。 |
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b*****t
发帖数: 3928 | 21 If it is a problem, you can use advanced feature, to delay or advance the
audio track relative to the video.
3. The source video file is not audio-video synchronous, can I fix it?
- Yes. Highlight the video file and right click on it. On the popup menu
select "Advanced" item. Then you can set audio delay number in milliseconds
(1 second = 1000 milliseconds) on the following dialog box. The value can be
zero, positive or negative. For example, if you set the audio delay number
to 200, you will he... 阅读全帖 |
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s**s
发帖数: 404 | 22 来自主题: EnglishChat版 - 问个弱问题 Please refer to wikipedia:
http://en.wikipedia.org/wiki/Inverse_element
"Every real number s has a additive inverse given by -x. Every nonzero real
number x has a multiplicative inverse give by 1/x. By contrast, zero has no
multiplicative inverse."
"A square matrix M with entries in a field K is invertible if and only if
its determinant is different from zero. If the determinant of M is zero, it
is impossible for it to have a one-sided inverse; therefore a eft inverse or
right inverse implies th |
|
v******i
发帖数: 1246 | 23 Vincent says:
t test
Vincent says:
usually we talk about two sample mean t test
Vincent says:
which is the simplest sample
Vincent says:
here H0: mean 1 = mean 2
Vincent says:
under the null hypothesis
Vincent says:
the T statistics is t distribution
Vincent says:
because as you can see
Vincent says:
bar X1 - bar X2
Vincent says:
will be normal with mean of 0
Vincent says:
instead of nonzero mean
vivi|咖啡机陪我到天明 says:
恩对 |
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p*******5
发帖数: 6446 | 24 如果你说的是经典意义上的质量，那爱因斯坦的质能转化方程已经宣告了经典质量不守
恒了。如果你说的是相对论意义下的质量,那么我在网上搜到这个：
The existence of the Higgs boson has no consequence for the law of
conservation of mass (which was modified after Einstein introduced
relativity to the law of conservation of mass-energy, or relativistic mass).
This law still holds.
The Higgs boson is simply a particle which is thought to be found everywhere
(even in a vacuum) - we say that it has a nonzero vacuum expectation value.
It has a mass itself, and all other particle... 阅读全帖 |
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z*****n
发帖数: 7639 | 25 算出真正的CRC校验错误率是很麻烦的。
对于一个N比特的CRC校验码，它可以检测出所有字长
小于N比特的burst error。对于字长大于等于N比特的
错误，只有当错误字的polynomial可以被CRC生成码的
polynomial可以整除的时候，CRC校验failure才会发生。
所以CRC校验失败率是
\eta = (prob. of divisible error pattern)/(prob. of all error pattern)
当然，这两个probability都跟BER有关。
举个简单例子，如果G(x)=x+1 （两位CRC generator，
一位冗余码，等同于parity校验），3位信息比特。
总字长4比特。BER=p。
出现1比特错误的概率是C(4,1)*p,
prob. of 2-bit error = C(4,2)*p^2,
prob. of 3-bit error = C(4,3)*p^3,
prob. of 4-bit error = C(4,4)*p^4,
All 1-bit errors can be correctly detected, ... 阅读全帖 |
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y****i
发帖数: 156 | 26 kbhit: check keyboard input
getch: get the key.
You can find help in MSDN or turboc C
// MSDN example
/* KBHIT.C: This program loops until the user
* presses a key. If _kbhit returns nonzero, a
* keystroke is waiting in the buffer. The program
* can call _getch or _getche to get the keystroke.
*/
#include
#include
void main( void )
{
/* Display message until key is pressed. */
while( !_kbhit() )
_cputs( "Hit me!! " );
/* Use _getch to throw key away. */
prin |
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n**h
发帖数: 237 | 27 谢谢回复。
不过find 好像是用来找nonzero元素的吧？ |
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n**h
发帖数: 237 | 28 还是没看到我要的功能啊。find函数解释第一行就是：Find indices and values of
nonzero elements。
看了description也没有实现我要的功能。请大侠明示。 |
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s******u
发帖数: 179 | 29 在fortran 90中，我将一个稀疏矩阵存成下面的数据格式：
TYPE:: rsm !Real sparse matrix
integer:: numbers !number of nonzero value in the matrix
integer,dimension(:),pointer::rows
integer,dimension(:),pointer::columns
real ,dimension(:),pointer::values
END TYPE rsm
然后用指针读取这个矩阵
TYPE:: rsmptr
type(rsm),pointer::p
END TYPE rsmptr
每次读取都是从第一个到后一个顺序读取。后面的程序中要对这个矩阵多次重复的读取(且是在内存中)
，这样的存法，读取的效率不怎么高。我也试过把一个矩阵中的元素存成一个node的数
据结构：
type:: node
integer :: rows
integer |
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M*******r
发帖数: 165 | 30 I am calling a exe from python, the exe would occasionally return a nonzero
value and been raised as error. The exe is written in c++ and the main
function is like:
int main(int argc, char *argv[]) {
xxxxxxxxxxxxxxxxxxxxx
return 0;
}
I suspected there is some memory leak in the code, but no warning no error
reported when I run it in debug/release mode...
BTW I'm working in VS12 environment. |
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n*****u
发帖数: 465 | 31 内存漏不会导致出错,这种随机出错十有八九是变量没初始化
nonzero |
|
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M*******r
发帖数: 165 | 33 I am calling a exe from python, the exe would occasionally return a nonzero
value and been raised as error. The exe is written in c++ and the main
function is like:
int main(int argc, char *argv[]) {
xxxxxxxxxxxxxxxxxxxxx
return 0;
}
I suspected there is some memory leak in the code, but no warning no error
reported when I run it in debug/release mode...
BTW I'm working in VS12 environment. |
|
n*****u
发帖数: 465 | 34 内存漏不会导致出错,这种随机出错十有八九是变量没初始化
nonzero |
|
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g****t
发帖数: 31659 | 36 假设所有确定性图灵机的结果的集合是A。
那么有限输入的随机图灵机的结果属于A。
因为随机数是有限输入的，所以可列举成多个确定性图灵机。
所以其结果已经包含在A内。尽管它是多个结果。
So it is clear that Random machine can not output an un-computable number.
Even the probability version is a NO.
"Supposing that we give a Turing machine random input, is it possible for
the machine's output to be complete and consistent with nonzero probability?
The answer is no." By a theorem due to de Leeuw, Moore, Shannon, and Shapiro
(1956)
http://mathoverflow.net/questions/224143/can-a-stochastic-tur... 阅读全帖 |
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w*******n
发帖数: 7 | 37 x1,y1,x2,y2 are in R3,
x1 and y1 are linearly independent,
x2 and y2 are linearly independent,
Consider two planes P1=(x1, y1), P2=(x2,y2).
Suppose we need to find a nonzero vector v in R3 that lies in the intersection
of P1 and P2. Devise a method for solving this problem by reducing it to the
computation of QR factorization of three 3by2 matrices. |
|
f**d
发帖数: 768 | 38 【 以下文字转载自 Statistics 讨论区 】
【 原文由 fyld 所发表 】
通过这种方法怎么计算entropy?
感谢！
或如何理解下面导出的Nc and S?
Suppose there n particles randomly distributed in a region of N positions.
Even if n is much smaller than N, there is a nonzero chance
for coincidence, i.e., some positions will get more than one particles.
Since the probability for a particle to fall in any given position is 1/N,
the number of coincidences is easily estimated by:
Nc=n(n-1)/2 *1/N
(why?)
Let us define R to be the coincidence rate which is the |
|
d****a
发帖数: 23 | 39 It is an 3D elliptic problem with periodic boundary conditions in lateral
boundaries and fixed top and bottom boundary condtions. After discretizing
by finite difference method, I get a big coefficient matrix with 39 nonzero
elements in each row. The matrix has dimension about 75,0000. Now the
problem is to solve the sparse linear system. However, this matrix elements
have a large numerical range, spaning 10 orders of magnitude. It is
nonsymmetric, not diagonally dominant, and not positive defin |
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b***e
发帖数: 38 | 40 Perhaps you need to go back to physics or work on basis functions to make
the matrix better conditioned.
nonzero
elements
Sparse |
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s**i
发帖数: 381 | 41 For example, one matrix is 2,170,159 X 2,170,159
it has 58,400,311 nonzeros
using preconditioned conjugate gradient method
it converges in 7 iterations.
If I use 32 processes, it only takes 0.28 seconds.
If I use 2 processes, it takes 5.29 seconds
The serial version converges in 4 iterations, taking 7.7 seconds. |
|
w*******U
发帖数: 256 | 42 I'm a beginner of the 3D DNS with the pseudo-spectral method. I calculated
the freely decaying flow. If the nonlinear inertial force is set to be zero
then the velocity divergence (sum |k dot u_k|, where u_k is velocity in
spectral space) is zero; but if the inertial force (or Re) increases then
the divergence (sum |k dot u_k|) increases. Then I calculated the flow
driven by a prescribed forcing and the divergence is zero.
So it seems that it is more difficult to resolve the freely decaying flow... 阅读全帖 |
|
|
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m*d
发帖数: 7 | 45 请问一个分布
Independent Gaussian (x) Gaussian (Both Have Nonzero Mean and Identical
Variance)
本来在《Probability Distributions Involving Gaussian Random Variables: A
Handbook for Engineers and Scientists》里有，可是学校图书馆里那本书被借走了
，要等近一个月，那位大侠知道，请不吝赐教，谢谢！ |
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a*****0
发帖数: 660 | 46 我发现如果把cmin值从0改成0.005pf， 或者是把accuracy改用liberal，则仿真都能正
常进行，但得出来的结果差得很远。这是我google出来的关于cmin说明：
If the circuit you are simulating can have infinitely fast transitions (for
example, a circuit that contains nodes with no capacitance), Spectre might
have convergence problems. To avoid this, you must prevent the circuit from
responding instantaneously. You can accomplish this by setting `cmin', the
minimum capacitance to ground at each node, to a physically reasonable
nonzero value. This often significa |
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b**s
发帖数: 589 | 47 Find two definition of gel
1. A gel is a colloidal system with a finite, usually rather small, yield
stress. Materials such as silica gel which have passed a gel stage during
preparation, are improperly called gels.
2. Rheologically, a sample is said to form a gel when it acquires a nonzero
shear modulus
on
(or
frequency,
at |
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n******d
发帖数: 244 | 48 There is no difference when det A=0.
Since you can consider A+tI, which has nonzero det
when t is small. then we have
det (adj(A+tI))=det (A+tI)^{n-1}
Then let t tends to 0.
by |
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y**t
发帖数: 50 | 49 Suppose (f(x))' represents the derivative of f w.r.t. x,
then your expression is equal to const*(x(1-x)')'|(x=1) where const
is a nonzero constant. |
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