w**********r
发帖数: 128 | 1 In geometric analysis, there is a well known Yamabe problem. First Yamabe
gave a wrong proof, later the final correct proof was given by Rick Schoen
using the Positive Mass theorem (which is still open for dimensions higher
than 7). The Yamabe problem is to prove the existence result of an equation
(Yamabe equation). After proving the Yamabe problem, Schoen conjectured that
all the solutions to the yamabe equation are uniformly bounded except for
one case. Recently it was proved to be wrong. Sch... 阅读全帖 |
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d**e
发帖数: 2420 | 2 文章仍然可以下载，打上了RETRACTED标识。第一次见着数学论文一稿多投，三波人，
居然在那么短时间内两次投同一个杂志Journal of Computational and Applied
Mathematics，看来缺少沟通呀，太搞了。
http://xys.org/xys/ebooks/others/science/dajia12/wanglijuan.txt
一鱼三吃、五人共享
作者：卿本佳人
一篇文发到三份期刊刊登，都被撤文了。涉及抄袭的五人是：
北京首都师范大学数学系 及 浙江嘉兴 嘉兴学院 数理与信息工程学院 王立娟
湖南省常德市 湖南文理学院 数学与计算科学学院 彭乐群
浙江嘉兴 嘉兴学院 数理与信息工程学院 王文涛
浙江嘉兴 嘉兴学院 数理与信息工程学院 乐光学
广东广州 广东工业大学 应用数学学院 欧春霞
Asymptotic behavior of solutions to a system of differential equations with
state-dependent delays
Lijuan Wang, Department of Ma... 阅读全帖 |
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N******n
发帖数: 3003 | 3 Does the second equation have any appropriate assumption to be right?
the paper mentioned the rightness of second equation in the context of fist
one.
does anyone have idea of the derivation of second equation?
3x |
|
N******n
发帖数: 3003 | 4 Does the second equation have any appropriate assumption to be right?
the paper mentioned the rightness of second equation in the context of fist
one.
does anyone have idea of the derivation of second equation?
3x |
|
J*******4
发帖数: 110 | 5 Thanks to Schiele for commenting!
The characteristic equation is derived from the following linear system of
delay differential equations:
\dot{z_1}(t) = z_1(t) + z_2(t-1)
\dot{z_2}(t) = z_2(t) + z_3(t-1)
\dot{z_3}(t) = z_3(t) - z_1(t-1)
The method I used to determine the double zeros of the characteristic
equation is from several papers (for example, you can find it from this
paper: http://iopscience.iop.org/0951-7715/21/11/010/). Meanwhile, it is also one of the conditions to determine the dou... 阅读全帖 |
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f*******g
发帖数: 55 | 6 Consider a deterministic infinite-horizon average cost problem.
Given a policy u, the state will converge to x0. Then in order to verify the
optimality of u, do we have to check the optimality equation (Bellman's
equation) for all the states in the state space, or do we just need to check
the equation for x0?
Thank you. |
|
m******t
发帖数: 273 | 7 【 以下文字转载自 Quant 讨论区 】
发信人: myregmit (myregmit), 信区: Quant
标 题: solve integral eq. embeeded with another integral eq.
发信站: BBS 未名空间站 (Sun Mar 23 14:20:18 2014, 美东)
I need to solve an integral equation embedded with another integral equation
by python 3.2 in win7.
There are 2 integral equations.
The code is here:
import numpy as np
from scipy.optimize.minpack import fsolve
from numpy import exp
from scipy.integrate.quadpack import quad
import matplotlib.pyplot as plt
impor... 阅读全帖 |
|
x********i
发帖数: 905 | 8 1950 Shiing-shen Chern, Differential Geometry of Fiber Bundles.
1970 Shiing-shen Chern, Differential Geometry: Its Past and Its Future.
1978 Shing-Tung Yau, The Role of Partial Differential Equations in
Differential Geometry.
1983 Wu-chung Hsiang, Geometric Applications of Algebraic K-Theory.
1983 Yum-Tong Siu, Some Recent Developments in Complex Differential Geometry.
2002 Sun-Yung Alice Chang and Paul Chien-Ping Yang, Non-linear Partial
Differential Equations in Conformal Geometry.
2002 Yum-To... 阅读全帖 |
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o*******w
发帖数: 349 | 9 You can use coordinate transformation on {x,y} to change the original
equation to
dx/dt = a(1-x-y)x - b1*x,
dy/dt = a(1-x-y)y - b2*y,
(i.e. we can only consider the case of a1=a2)
Dividing by x (and y respectively) both hand sides yields
(dx/dt)/x + b1 = a(1-x-y)
(dy/dt)/y + b2 = a(1-x-y)
Thus you have
(dx/dt)/x + b1 = (dy/dt)/y + b2
i.e.
d/dt (ln x + b1*t) = d/dt (ln y + b2*t)
=> d/dt (ln x + b1*t) - d/dt(ln y + b2*t) = 0
ln(x/y) + [b1 - b2]*t = ... 阅读全帖 |
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x********i
发帖数: 905 | 10 2015 Abel Prize to Nash and Nirenberg
Wednesday March 25th 2015
John NashThe Norwegian Academy of Sciences and Letters will award the 2015
Abel Prize to John F. Nash Jr. (left), Princeton University, and Louis
Nirenberg (right), Courant Institute, New York University, "for striking and
seminal contributions to the theory of nonlinear partial differential
equations and its applications to geometric analysis." (Photos: Nash: ©
Peter Badge/Typos 1 in coop. with the HLF - all rights reserved 20... 阅读全帖 |
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x********i
发帖数: 905 | 11 http://www.ams.org/news?news_id=3272
Charles Fefferman (left), Princeton University, and Richard Schoen (right),
University of California, Irivine, have been named the winners of the 2017
Wolf Prize in Mathematics for "their striking contributions to analysis and
geometry." The two will share the US$100,000 prize. (Photos courtesy of
Princeton University and the University of California, Irvine.)
The citation for Charles Fefferman notes that he has "made major
contributions to several fields, in... 阅读全帖 |
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a****t
发帖数: 720 | 12 I am mostly interested in the dynamics of the droplet. So I will solve the
Navier-Stokes equation coupled with electrohydrodynamic force. Yes. I think
the electric field is static and is solved by Laplace equation. I did CFD
before. This research may require me couple the electric field effect into the NS momentum equation.
Are you working now?
electrical |
|
l******e
发帖数: 14 | 13 Hi,
After second thought, I think you were right about the mass flow rate Q(t).
It is a function of time and it shall determine the pressure distribution P(
x,t) and the dynamics of the piston.
Here is my thinking now. Two stages have to be assumed to make things easy.
Stage 1: Right after the valve opens, pressure propagates instantly through
the whole hose. Piston does not move yet. All the mass flow is from the hose
expansion.
Stage 2: Piston starts to move. From here, we shall be able to bui... 阅读全帖 |
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N***r
发帖数: 2539 | 14 是，严格来讲你这个确实不是exact的伯努力方程。
严格的伯努力方程的推导有两种，无粘流体机械能守恒，或者欧拉方程里的动量方程沿
流线的积分。两种情况得到的最终方程是一样的，对不可压缩流体。
P_static + 1/2 rho u^2 + rho*g*h = constant
注意这里头一个非常重要的假定就是 “无粘”。
你的方程一般称为Bernoulli's equation with head loss，也就是考虑能量损失的伯
努力方程，一般很少被称为energy conservation equation，或许称之为mechnical
energy conservation是可能的（我不是很清楚）。在民用设计，计算里很常用，比如
说消防队计算水头什么的。湍流和层流并不是判断伯努力方程能否适用的准则，比如在
一段直圆管内，只要有摩擦，不管是层流还是湍流，严格的伯努力方程都失效，因为你
不能假定 “无粘流体”。这个时候要考虑沿程损失，而且要使用Bernoulli's
equation with head loss，就是这样的：
P_s1 + 1/2 rho u1^2 + rho*g... 阅读全帖 |
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b********7
发帖数: 2404 | 15 LOL 2 & 13:
微粒 and 电磁波 are classical concepts, related with Newton equation and
Maxwell equation, respectively.
Up to now, we know that the light is a quantum particle, but what equation? |
|
a***r
发帖数: 594 | 16 from what you said, you have no understanding in the big picture of quant
finance. you do not appear to have studied physics in any depth AT ALL either.
many separate the finance world into buy side and sell side. I happen to
have worked on both sides.
the training a physicist receives makes him/her a very good fit for sell
side quant roles.
In this part of the world, one does not try to forecast the future returns
on financial instruments. Instead one focuses on understanding the behavior
of th... 阅读全帖 |
|
q**********7
发帖数: 857 | 17 Weinberg's Quantum Theory of Fields VI.
Page 78. He gave the last equation but he didn't prove it, although he
qualitatively explained it. I tried to prove it quantitatively but I failed.
Also, in page 80, he didn't prove the first equation either. I need help
with those two equations.
The two pictures are from Google http://books.google.com/books?id=NcH...page&q&f=false |
|
l***y
发帖数: 1166 | 18 Non-hertzian waves
非赫兹波
In the Responses to Questions on December 20, 2000 of various authors and
researchers concerning Dr. Tesla, it is reported that Tesla's concept of "
electromagnetic momentum" appears to have been gleamed from Maxwell's
original work (ed. the equation usually referred to as the Maxwell's
equation in use today were written by Oliver Heaviside and could rightly
then be called the "Maxwell-Heaviside equations"). Tesla was familiar with
the quaternion notation in Maxwell's wor... 阅读全帖 |
|
|
d**s
发帖数: 920 | 20 Hi,
Is this Fokker-Planker (or Kolmogorov
forward equation) equation related to BS equation ?
Thanks. |
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t*******e
发帖数: 172 | 21 There is a tedious method, fix any integer d.
Let E_{k} be the expectation of the # of d continuous head.
Then
For N>=k+1;
E_{N}= ( \sum_{j=1,2,..N-1} p^{j-1}(1-p) E_{N-j} ) + p^{k}(1-p).
with
E_{j}=0 for j=1,2,...k-1. and
E_{k}=p^{k};
Now the rest is how to solve this equation. It is a tedious reduction
process.
First, let A_{N}= E_{N}/p^{N}, the equation becomes:
A_{N}= (1-p)/p \sum_{j=1,2...N-1} A_{j} + p^{k}(1-p)/p^{N}
Second, let S_{N-1}=\sum_{j=1,...,N-1} A_{j}, then the equation becom |
|
l******i
发帖数: 1404 | 22 As long as
dXt=miu(t,Xt)dt+sigma(t,Xt)dWt
where miu and sigma are deterministic functions of (t,Xt),
(note that only adapted process property is not enough.)
Xt is a markov process.
You can convert the stochastic problem into a PDE framework:
Solve the classic Kolmogorov backward equation (KBE)
or Kolmogorov forward equation (KFE)
to get the transition density function p(x,t) explicitly.
(I usually use KFE, known as Fokker–Planck equation.)
Here is some introduction:
http://en.wikipedia.org/wiki... 阅读全帖 |
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M****i
发帖数: 58 | 23 This kind of equation can be solved by the method of integrating factor.
For your problem, choose the integrating factor z(t)=exp(-w(t)+t/2) and then
use Ito's formula to get d(x(t)z(t))=z(t)dt (this is only an ODE). So that
the solution of your equation is given by
x(t)=z(t)^{-1}(x(0)z(0)+\int_0^t z(s) ds).
In fact, the same idea can be used to sovle the SDEs of the form
dx(t)=f(t,x(t))dt+c(t)x(t)dw(t),
where f and c are continuous functions.
In this general case, the integrating factor is
z(t)... 阅读全帖 |
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M****i
发帖数: 58 | 24 You are welcome.
An advantage of the above generic method is that it can be used to solve
some nonlinear SDEs. For example:
dx(t)=x(t)^rdt+ax(t)dw(t), x_0=x>0,
Where r and a are constants.
(This is a good example to understand
how does the method work.)
Some ideas to your questions:
<1> The ODE dy(t)=z(t)f(t,y(t)/z(t))dt should be considered pathwisely, i.e.
for every fixed sample point $\omega$,
we regard it as a deterministic ODE and try to solve it.
So it doesn't matter that the BM involes. ... 阅读全帖 |
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w***a
发帖数: 226 | 25 是两回事。
我第一次接触Ito calculus是在物理系研究生一年级的一门偏应用的统计物理课上
用的教材是van kampen 的stochastic processes in physics and chemistry
很多统计物理模型都是用langevin equation，fokker－planck equation，master
equation
我没有说物理系一定要求上哪门课。比如随机过程，好象就没在物理系开过。
但做统计物理的同学一般都应该自己学过用过吧 |
|
i**w
发帖数: 71 | 26 parabolic pde with constant coefficients can always be transformed into heat
equation. thus solving heat equation solves all parabolic in some sense.
Transformation from general parabolic with (x,t) dependent coefficients to
heat like equation is not so obvious, but it is probably not so wild to
claim it true. any one from math?
|
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i**w
发帖数: 71 | 27 parabolic pde with constant coefficients can always be transformed into heat
equation. thus solving heat equation solves all parabolic in some sense.
Transformation from general parabolic with (x,t) dependent coefficients to
heat like equation is not so obvious, but it is probably not so wild to
claim it true. any one from math?
|
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r******g
发帖数: 13 | 28 Thank you very much, kinecty, zan
didn't realize the two roots in different range
then it should be the sum of the two roots substitution, it will cancel out
the second parts, get equation (2), why is the difference? in both roots,
the range for v is (2, \infty)? equation (7) gives that v is in (-\infty, -2), then u is negative
what's wrong with equation (3)? related to "the substitution is not
monotonic"? |
|
|
m******t
发帖数: 273 | 30 I need to solve an integral equation embedded with another integral equation
by python 3.2 in win7.
There are 2 integral equations.
The code is here:
import numpy as np
from scipy.optimize.minpack import fsolve
from numpy import exp
from scipy.integrate.quadpack import quad
import matplotlib.pyplot as plt
import sympy as syp
lb = 0
def integrand2(x, a):
print("integrand2 called")
return x**(a-1) * exp(-x)
def integrand1(x, b, c):
print(... 阅读全帖 |
|
L*******t
发帖数: 2385 | 31 就是假设股票价格服从一个stochastic differential equation，然后这个equation的
参数依赖于一些状态变量，这些状态变量的stochastic differential equation有以下
的形式：
dY(t) = a(t,Y(t))dt+b(t,Y(t))dW(t)
a和b只依赖于Y(t)的当前值，而不依赖Y的历史路径。这个就是我所说的markov
structure了
我觉得业界可能不会用dynamic hedging这一套理论因为这套理论用的话要specify一个
utility function，这个没办法琢磨。。
所以MV with constraints可能比较好一些。但是现在还不知道有intertemporal
hedging，具体效果会好还是会不好。。 |
|
s***e
发帖数: 911 | 32
y{\dot}a=d is one equation:
a1*y1+a2*y2+a3*y3=d;
y{\cross}a are three equations:
a3*y2-a2*y3=c1
-a3*y1+a1*y3=c2
a2*y1-a1*y2=c3.
The matrix A={{0,a3,-a2},{-a3,0,a1},{a2,-a1,0}}is singhular(the rank is 2.
So you have to solve this equation accampany with a1*y1+a2*y2+a3*y3=d.
Express y2,y3 by y1:
y2=(a2/a1)*y1-c3/a1;
y3=(a3/a1)*y1+c2/a1.
Then
a1*y1+a2*y2+a3*y3={y1*a1+[(a2^2/a1)*y1-c3*a2/a1]+[(a3^2/a1)*y1+c2*a3/a1]}
=d
so,
y1=[a1*d-(c \cross a)_1]/|a|^2;
Then u can get y2,y3 by sim |
|
r*f
发帖数: 731 | 33 谢了.我知道你给我的方程是mass conservation equation.
but the \rho in this equation is the function of x and t or of a and t?
You know, the answer must be expressed in terms of x=x(a,t) and rho=rho(a,t).
Actually, the second question of this problem is :
write the conservation of mass equation.
And I have written it as d{\rho|/dt+div(\rho*u)=0.
But I don't know whether \rho must be the function of x and t or it can be the
function of a and t.
In our general problems, \rho always is the function of x and t, t |
|
d*z
发帖数: 150 | 34 No!!!
Because each points only satisfy two equations, not five
equations.
How could u construct the result equation? Not so easy. And
I think
it is not convenient to use Projection Geometry, because it
will
transform circles to ellipses. |
|
h*l
发帖数: 19 | 35 1. The 5 equations below are for 5 circles, pairs
of them can be used for those 10 points, but not my
intension.(at most use like (1)-(2) to be as the
equation for "gen1 zhou2") As I said, I failed to
construct the final circle equation although I believe.
2. There are techniques in Projection Geometry other
than like "warping transform" (Fang3 She4 Bian4 Huan4)
ect. I think it should be in Feng's book or other
books. I regret I did not learn that far long time ago.
3. By the way, someone |
|
h***o
发帖数: 539 | 36 The first assumption is that your case is one-dimensional
Thus you need a relation (ie, a equation) to confine your
particle. If you have this equation, say, it's periodic,
then you can get the magnitude of v and direction of v.
The Hamiltonian is not such a equation.
You introduce a new variable H into your system. |
|
y***u
发帖数: 25 | 37 V=0 as ra
say, the wave function is w=R(r)O(o), o is the angle
By using the polar coordinate the equation becomes
R''O+R'O/r+RO''/r^2=(V-k^2)RO
where V is the potential,which is zero here. k^2=2mE/h^2
so
r^2*R''/R+r*R'/R+r^2*k^2=-O''/O=m^2
where m is an integer in order to keep O(o+2*Pi)=O(o)
so
O(o)=Exp[I*m*o]
The radial equation is
R''+R'/r+[k^2-m^2/r^2]R=0
set r=x/k
R''+R'/x+[1-m^2/x^2]R=0
which is exactly the Bessel equation. The two linearly independent solutions
are
J_ |
|
t******y
发帖数: 239 | 38 I went through the problem again and realized that the equation
n(n-1)[1-(n-1)x]^(n-1) was indeed for the distribution of the
smallest distance, instead of the nearest neighbor distance. When n=2,
they are equivalent to each other, but when n>2, they should be
different (or not? I still cannot picture it clearly).
How did you get your equation? It seems very simple. Yesturday I got
an integration equation, and I am still working on it. It's likely that
even I can find the answer, the result will |
|
t**a
发帖数: 6 | 39 my IV is continuous variable. Maybe I should say GLM upstairs. I think in
SPSS, they are the same procedures.
I cannot use SEM because my sample size too small.
Also, anyone heard about SUR (seemingly unrelated regression)? it allows the
error of each equation to be correlated.SUR is an extension of the linear
regression model which allows correlated errors between equations.
I think in GLM, all DVs are entered into one same model, where as in SUR,
there are a few different equations/models with |
|
l*********g
发帖数: 177 | 40 向各位请教一下：
本人在sas中进行gmm estimation，用的是proc model的功能。但是现在有个麻烦的问
题就是， 根据我需要estimate的model，在我写gmm 的每个moment condition
equations 的时候会需要用到matrix的计算（比如inverse， multiplication等）。然
而似乎在proc model中写那些moment condition equations 只能写成用1维的量表达的
式子，这就造成我的问题：如果把比如matrix inverse之类的计算用1维的式子表示会
变得极为繁琐和庞大。
我知道sas中有个iml进行矩阵运算的，但是那个iml并没有和proc model联系在一起。
请问有没有人知道根据我的情况，能怎样在proc model中实现gmm还能用矩阵来方便描
述我的moment condition equations 啊？
谢谢帮助！ |
|
c*****a
发帖数: 16 | 41 First step: run a probit equation of participation using all the
observations. The estimates of from this probit model are then used to
construct consistent estimates of the inverse Mills ratio term.
Second step: Include the inverse Mills ratio and run the original regression
equation.
Question: do these two equations have to include the SAME control variables
(except IV)? |
|
c*******t
发帖数: 123 | 42 google
H-theorem boltzmann equation
H=int log(f(v))*Q(f,f) dv<=0;
H is the time-rate of entropy function, it only equals 0 for a Maxwellian
distribution.
And boltzmann equation is a general equation of gas dynamics. |
|
s******e
发帖数: 16668 | 43 原本想贴在这儿来着，后来担心歌太老。。。
帮主知道Damamine吗？
相对Dramamine来说，Walmart自己卖的Equate Motion Sickness Tablets要经济实惠很
多。
我姑姑也非常晕车晕机，她说Equate比Dramamine好。她是医生，我就信她的。自从学
会开车以后，我不再晕车了，但是依然晕机。所以，我常备Equate Motion Sickness
Tablets.
五岳我一岳都没有去过。。。太惭愧了。湖南好玩的地方多，而我连家隔壁的凤凰都还
没有去。 |
|
w*******y
发帖数: 60932 | 44 Brief Description
Microsoft Mathematics provides a graphing calculator that
plots in 2D and 3D, step-by-step equation solving, and useful tools to help
students with math and science studies.
Microsoft Mathematics provides a set of mathematical tools that help
students get school work done quickly and easily. With Microsoft
Mathematics, students can learn to solve equations step-by-step while
gaining a better understanding of fundamental concepts in pre-algebra,
algebra, t... 阅读全帖 |
|
m******t
发帖数: 273 | 45 【 以下文字转载自 Quant 讨论区 】
发信人: myregmit (myregmit), 信区: Quant
标 题: solve integral eq. embeeded with another integral eq.
发信站: BBS 未名空间站 (Sun Mar 23 14:20:18 2014, 美东)
I need to solve an integral equation embedded with another integral equation
by python 3.2 in win7.
There are 2 integral equations.
The code is here:
import numpy as np
from scipy.optimize.minpack import fsolve
from numpy import exp
from scipy.integrate.quadpack import quad
import matplotlib.pyplot as plt
impor... 阅读全帖 |
|
y***y
发帖数: 198 | 46 ☆─────────────────────────────────────☆
nde (nonlinear differential equation) 于 (Tue Jul 22 22:50:27 2008) 提到:
为什么理论书籍，诸子百家的文献流传了很多，但是技术方面的文献却不见有流传呢？
☆─────────────────────────────────────☆
nayiwan (那一晚) 于 (Tue Jul 22 22:53:16 2008) 提到:
比如说鲁工秘录
☆─────────────────────────────────────☆
nde (nonlinear differential equation) 于 (Wed Jul 23 08:58:15 2008) 提到:
你也就能列举一个。
我不用google都能写出十部以上的先秦的诸子百家的著作。
☆─────────────────────────────────────☆
iMan (iMan) 于 (Wed Jul 23 09:53:59 2008) 提到 |
|
w*********g
发帖数: 30882 | 47 高歌，现任北京航空航天大学能源动力学院动力工程及工程热物理学科一级责任教授，
航空发动机气动热力国防重点实验室副主任，长期从事动力工程、工程热物理及流体力
学领域的教学与科研工作，并在基础科研和多学科的应用技术领域取得了一系列国际领
先水平的创新性科研成果。
他在1984年发明的"沙丘驻涡火焰稳定器"，获国家发明一等奖，钱学森同志称之为"一
项长中国人志气的重要发明"。该成果广泛应用于我国多种军用航空发动机中，取得了
数以亿元计的经济效益，至今仍保有先进水平。本刊记者于今年10月采访了高歌教授，
了解到了他近期从事的一些前沿科研工作的最新进展，尤其是他对龙卷风的研究及其工
程应用价值，让人耳目一新。
高歌教授在采访中提到，传统的航空发动机技术虽然还在不停地改进提高之中，但
受到原理和材料工艺上的限制，已经逐渐逼近了性能发展的极限。目前虽然涌现出一些
新型航空发动机技术，但仍然没有走出依靠压力膨胀过程来实现热功转换的思路。他强
调，人们应该另辟蹊径，寻找其他可用的工作原理。为此，他研究了自然界龙卷风的形
成与强化机制，发明了一项称为"余热增推"的技术，直接利用龙卷旋涡实现热功转换并
提取... 阅读全帖 |
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C******e
发帖数: 750 | 48 首先，Physics Reports不是Physics Report, Reviews of Modern Physics不是Modern
Physics Review;
其次，搞凝聚态物理（包括低维系统）的会常用Dirac equation, Schroedinger
equation，Einstein relation（质能方程姑且不论），还不是Nature（包括Nat Phys
，Nat Nano，Nat Mater）、Science、RMP、PNAS狂发？！谁tmd管那个什么规范场理论
？难道相关审稿都是脑残？
Last but not least，什么样的物理PhD可以不懂爱因斯坦（包括相对论、光电效应、
质能关系、扩散输运理论等）？有多少比例的物理PhD需要规范场？
在我个人看来，老杨撑死和安德森一个档次，别再瞎捧了。
展开标准论述。
Physics Report、Modern Physics Review、Nature Physics这类，就是PRL/PR都进不
了。
场。
对中国而言，杨也就是花瓶，跟邓稼先、于民、钱学森不能比。 |
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d*b
发帖数: 21830 | 49 不要说Bragg equation了，理论物理phd能不看书写出Schrondinger equation的人聊聊
无几。你就更别提了。。。 |
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v*****s
发帖数: 20290 | 50 不至于，Schrondinger equation很好写的，特别是含时的，如果不需要写出哈密尔顿
算符的具体形式，绝大多数物理本科生都能写出来，更别说理论物理phd了。你要说理
论物理phd大部分写不出bragg equation，我还是相信的。 |
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