z****j
发帖数: 111 | 1 可能是我理解有点问题... 不过像fib（n） = fib（n-1） + fib（n-2）这样的递归式
它的optimal点体现在哪里呢？这个也可以算是optimal substructure吗 |
|
l******9
发帖数: 579 | 2 【 以下文字转载自 Quant 讨论区 】
发信人: light009 (light009), 信区: Quant
标 题: SQL server optimal query design
发信站: BBS 未名空间站 (Fri Jul 4 12:54:15 2014, 美东)
I need do some SQL server query design.
For doing the same query, there may be many different kinds of query design.
But, I need to learn which kinds of query design/implementation are optimal
for performance.
Could anybody recommend some books/publications to learn how to do that ?
Any help would be appreciated. |
|
d*********e
发帖数: 352 | 3 感觉完全看面试官喜好。
有的是做出来就好，那brute force一般写习惯了不容易出错，一遍过还是可以做到的。
有的一定要optimal, 没见过的题只能摸索着写，容易出bug要调试，然后feedback就是
"your debugging skill is good".
碰到要求bug free + optimal的就只能move on了。
国人何必为难国人。 |
|
J********h
发帖数: 93 | 4 我们比较prefer数学物理背景的有较强编程能力的。公司比较稳定,福利不错，工作环
境较好。简历请发到[email protected]/* */。
Senior Engineer (Modeling / Optimization)
Experience
3+ year experience in C++ and/or other object-oriented software development.
Solid understanding in data structures and algorithms. Experience in
developing and debugging multi-threaded/parallel applications. Familiar with
SQL, UNIX environment and scripting languages. Experience in image
processing, computational geometry, optimization, numerical methods,
scienti... 阅读全帖 |
|
a*******u
发帖数: 7 | 5 you may want to try financial industry, especially asset managers.
Quantitative managers need to optimize their portfolios regularly. Of course
, not every quantitative manager needs to build their own optimization
machinery, but some do.
Also commercial banks also have such needs.
Another industry with such need I am aware of is Medicinal Chemistry where
chemistry and pharmacy meet. Try out some large pharmaceutical companies. |
|
k********h
发帖数: 22 | 6 About Us:
ROBLOX is a leading user-generated gaming site that makes players the
architects of their own 3D worlds, drawing over one billion page views and
21 million in-game hours each month. The site is ranked #1 in the US for
total engagement time within the 8-14 year old segment, and is rapidly
growing in popularity amongst players aged 15+. Our vision is to become the
leader in user-generated gaming for all ages, around the world. On ROBLOX,
players use core building components to create ela... 阅读全帖 |
|
i*t
发帖数: 835 | 7 什么是optimal vitamin，我以为optimal 是一个牌子，但是看大家说好像是别的牌子 |
|
h***r
发帖数: 3688 | 8 不知道这个东西，看姐妹们介绍才知道。正好手上有个经典胖月底要过期，所以想如果
有货的话赶紧化了。结账的时候还跟出来一张3off15的胖子。我买两个蛋白粉超过35刀
了，能合并使用经典胖+3off15胖+机器刷出来的两张5off胖+厂家两张4off胖+20%off
Medicare胖？其中厂家胖虽然都是4off，但是分别从两个网站打的，图案号码以及名称
都不一样。一个是optimal solutions complete protein & Vitamin shake，还有一个
是any optimal solutions supplement.
另外百分胖只要在规定金额以内是不是所有原价东西都打折扣啊？
谢谢！ |
|
|
S******s
发帖数: 179 | 10 【 以下文字转载自 JobHunting 讨论区 】
发信人: Sounders (Sounders), 信区: JobHunting
标 题: [Hiring] Optimization Server Developer (Seattle)
关键字: job opening,hiring
发信站: BBS 未名空间站 (Wed Jan 20 23:08:04 2010, 美东)
Start up at Downtown Seattle, will sponser H1B VISA if you are pretty good.
If interested, send me your resume, I will give you a referral.
email: sounders.mitbbs at gmail.com
Optimization Server Developer (Seattle)
Do you like shaking up the status quo? How about shaking up the advertising
industry? Adver |
|
d****j
发帖数: 293 | 11 推荐审稿一篇：
Journal name: International Journal of Advanced Intelligence Paradigms
Paper keywords:
Optimization Algorithm
Mobility Robustness in cellular networks
Optimization with Self-Organizing Network (SON)
fuzzy logic and Partial Observed Markov Decision Process
站内联系 |
|
t**********3
发帖数: 12623 | 12 【 以下文字转载自 USANews 讨论区 】
发信人: yourtt (rainmaker), 信区: USANews
标 题: 'My son is not very optimal - he is very dead'
发信站: BBS 未名空间站 (Fri Oct 19 13:38:11 2012, 美东)
Mother of diplomat killed in Benghazi attack slams Obama's comment on raid
- President told Jon Stewart, 'If four Americans get killed, it's not
optimal'
- Remarks sparked massive backlash on social media
- Mother of slain diplomat Sean Smith says Obama was 'disrespectful'
http://www.dailymail.co.uk/news/article-2220241/Barack-Oba... 阅读全帖 |
|
|
t*******l
发帖数: 31 | 14 和生活中认识异性朋友相比，网络征友有以下缺点：
1.人与人之间没有credit和penalty.现实生活中，一般如果有共同的朋友，对对方的认
识是比较全面的，因为有太多的信息来源了。而网上征友是一对一进行的，RP好的根本
不占优势。而恰恰这个RP在以后的交往中又很重要，所以就出现了这种情况，网上交友
成了，不久就分了。有亏于人家的一方也没有受到任何RP道德上的惩罚，对他/她以后
的生活基本没有影响。
2.网上交友认识异性的cost太低。现实生活中，因为性格和时间等因素，要认识异性是
需要时间精力的,而且还要的试探对方是否已经有男女朋友或分析潜在的竞争对手。相
反，网络交友，很可能点几下鼠标就"认识"了一对异性，而且双方都是很明确地表明要
找男女朋友的。这种低cost，导致了对未来期望过高，总是希望再点几下鼠标就会有更
合适的。
3. 网络交友的Optimal Stopping Rule难以量化。因为1和2的原因，现实生活中认识异
性的pool变化缓慢，对pool中的异性信息充分，很容易确定一个Optimal Stopping
Rule。但是网络交友，由于理论上这个pool是无穷大，认识 |
|
D*******a
发帖数: 3688 | 15 【 以下文字转载自 EE 讨论区 】
发信人: DrumMania (嫑跑，兲), 信区: EE
标 题: MINLP里面如何证明local optimality
发信站: BBS 未名空间站 (Tue Mar 27 14:28:11 2007), 站内
发信人: DrumMania (嫑跑，兲), 信区: Mathematics
标 题: MINLP里面如何证明local optimality
发信站: BBS 未名空间站 (Tue Mar 27 14:28:06 2007), 转信
有这么一个MINLP问题：
min f(x,y)
Ax<=b
x ~ {0,1}
y ~ unconstrained real number
现在找到了一个解(x*,y*)，其中f'_y(x*,y*)=0，如果需要证明(x*,y*)是local
minimum，
还需要什么条件？
因为有整数，KKT定理没法apply，请问应该引用什么定理？
thanks a lot！ |
|
c*****r
发帖数: 4 | 16 【 以下文字转载自 JobHunting 讨论区,原文如下 】
发信人: Carrier (Enterprise), 信区: JobHunting
标 题: 求教数据库的query optimization 工作的面试
发信站: Unknown Space - 未名空间 (Wed Jun 9 22:13:13 2004) WWW-POST
各位数据库高手, 能不能指点一下会问什么? 有六个人面试, 每人半小时.
他们都精通Query optimization, 工作是数据库地层的query 的优化(不是DBA, 或数据库
应用). 我这方面经验也不多. 他们大致会问什么呢? 数据库基本知识? indexing, b
tree? C coding? Data Structure? Algorithm? Different Query algorithms? SQL? 东
西太多, 也很茫然, 希望能得到点指点. 多谢多谢!!!! |
|
c*****t
发帖数: 1879 | 17 【 以下文字转载自 CS 讨论区 】
发信人: coconut (向唐僧大师学习中), 信区: CS
标 题: 谁能推荐关于 sql query optimization 方面的书？
发信站: BBS 未名空间站 (Sat Aug 29 18:57:28 2009, 美东)
谁能推荐本 sql query optimization 方面的书？能有 parallel 部分的更好。
thx |
|
l******9
发帖数: 579 | 18 【 以下文字转载自 Quant 讨论区 】
发信人: light009 (light009), 信区: Quant
标 题: SQL server optimal query design
发信站: BBS 未名空间站 (Fri Jul 4 12:54:15 2014, 美东)
I need do some SQL server query design.
For doing the same query, there may be many different kinds of query design.
But, I need to learn which kinds of query design/implementation are optimal
for performance.
Could anybody recommend some books/publications to learn how to do that ?
Any help would be appreciated. |
|
a*****e
发帖数: 176 | 19 要optimize的方程中，有要求matrix inverse 的地方，
于是iteration的过程中，总是在optimal value出现之前，不停提示
warning: matrix is singular to working precision
How should I deal with this? |
|
y***a
发帖数: 840 | 20 compilers can be used to optimize this kind of code. But to say "it doesn't
matter actually" is really far-fetched. The fact is that the compielr can b
e easily confused and then gives up the optimizations that are easy from the
user point of view.
to do that, comipiler has to do good inlining to eliminate the member functi
on calls (many compiler does poor job on that).
oftentimes actually this is the easist thing, it has some benefit because it
eliminates function call overhead. but oftentimes |
|
l******9
发帖数: 579 | 21 【 以下文字转载自 Quant 讨论区 】
发信人: light009 (light009), 信区: Quant
标 题: SQL server optimal query design
发信站: BBS 未名空间站 (Fri Jul 4 12:54:15 2014, 美东)
I need do some SQL server query design.
For doing the same query, there may be many different kinds of query design.
But, I need to learn which kinds of query design/implementation are optimal
for performance.
Could anybody recommend some books/publications to learn how to do that ?
Any help would be appreciated. |
|
l**********t
发帖数: 5754 | 22 【 以下文字转载自 Economics 讨论区 】
发信人: littletshirt (小仙鹤), 信区: Economics
标 题: help: optimization with stochastic programming
发信站: BBS 未名空间站 (Wed Oct 21 08:13:07 2009, 美东)
I'm interested in using stochastic programming in an optimization problme.
Could someone with experience in this area recommend softwares/C++ libraries
? Does SAS or MatLab have packages for stochastic programming? Many thanks. |
|
s********w
发帖数: 487 | 23 一年多前的帖子被翻出来了，真不容易
太谢谢你了，讲得很具体
我已经来美国了，现在做的是control system那块
但是感觉我上的课，还有做的方向，和EE的control方向很像。现在基本上上的都是EE
的control的课程，以及应用数学开的optimization的课。还挺担心以后出去了竞争不
过EE的control的高手。所以现在在想尽量往化工的control那块靠拢
现在实验室主要做optimization，以及subspace的system identification的方向。也
不知道这个以后出路如何了... |
|
s********w
发帖数: 487 | 24 一年多前的帖子被翻出来了，真不容易
太谢谢你了，讲得很具体
我已经来美国了，现在做的是control system那块
但是感觉我上的课，还有做的方向，和EE的control方向很像。现在基本上上的都是EE
的control的课程，以及应用数学开的optimization的课。还挺担心以后出去了竞争不
过EE的control的高手。所以现在在想尽量往化工的control那块靠拢
现在实验室主要做optimization，以及subspace的system identification的方向。也
不知道这个以后出路如何了... |
|
t****n
发帖数: 39 | 25 Actually code optimization is machine dependent. However, for most popular
CPUs, the code written in a cache friendly manner could increase performance
significantly. For example, if you want calculate the following array
addition, C = A + B, and by switching off the compiler optimization,
code written as
do j = 1,jm
do i = 1,im
C(i,j) = A(i,j) + B(i,j)
end do
end do
would be way faster than
do i = 1,im
do j = 1,jm
C(i,j) = A(i,j) + B(i,j)
end do
end do
There are a lot of other t |
|
l******v
发帖数: 12 | 26 yeah, that's the row major and column major difference between C and Fortran.
btw, in Fortran 90 and some implementations of Fortran 77, array ops are much
simpler. just write:
c = a + b, if a, b, and c are of same form
dot_product(a, b) gives the dot product of two vectors of same length
mat_mul(a, b) gives the multiplication of two matrix
d = k*a, when k is scaler, a and d has same form
the optimization jobs are then handled by the complier
for
performance
optimization? |
|
o*****s
发帖数: 1445 | 27 I have a code like the following. But it is a linear constrained optimization
code. I want to solve nonlinear optimization. How can I change it? I knew
fmincon in matlab. Thanks a lot.
% [xmin,lambdamin,fxmin]=dnewtonlip('f','g',A,b,x0,tol)
%
% Given a function 'f', its gradient 'g', a feasible x0, and
% linear inequality constraints Ax>=b, use a discrete Newton method
% to minimize f, ending at a point xk, with
%
% |f(xk)-f(xk-1)| < tol*(1+|f(xk)|)
%
function [xmin,lambdamin,fxmin]=dn |
|
l***e
发帖数: 10 | 28 Hi, All:
I came up with an optimization problem min f(x)= 1/2 x' H x- abs(x) subject
to -c<=x<=c, and sum(x)=0. Here, H is a matrix, x is vector, c is bound.
It looks like quadratic programming. But not really.
I tried the "fmincon" in the optimzation toolbox of Matlab, but it can't
find a statisfactory solution. The problem is not convex ( I think), but
some optimization method should reach a good minima.
Anyone can help? Please! If anyone can solve this, it could be used in a
wonderful |
|
w****w
发帖数: 7 | 29 Could anyone please recommend some materials, books or papers, on
optimization algorithms which can produce robust results with respect to the
knowledge pre-acquired that describes the uncertainty of the subject? In
other words, deal with operation uncertainties in the optimization procedure.
Thank you very much! |
|
l**********t
发帖数: 5754 | 30 【 以下文字转载自 Economics 讨论区 】
发信人: littletshirt (小仙鹤), 信区: Economics
标 题: help: optimization with stochastic programming
发信站: BBS 未名空间站 (Wed Oct 21 08:13:07 2009, 美东)
I'm interested in using stochastic programming in an optimization problme.
Could someone with experience in this area recommend softwares/C++ libraries
? Does SAS or MatLab have packages for stochastic programming? Many thanks. |
|
a****f
发帖数: 944 | 31 When you do energy minimization problems, do you use built-in matlab
function or write your own gradient descent method ( or other methods)?
I use matlab function fmincon for a constrained optimization problem, but
the parameters don't change at all after optimization, except those that did
not satisfy the constraints are changed to meet the constraints.
Does anyone know the reason? |
|
k********h
发帖数: 22 | 32 About Us:
ROBLOX is a leading user-generated gaming site that makes players the
architects of their own 3D worlds, drawing over one billion page views and
21 million in-game hours each month. The site is ranked #1 in the US for
total engagement time within the 8-14 year old segment, and is rapidly
growing in popularity amongst players aged 15+. Our vision is to become the
leader in user-generated gaming for all ages, around the world. On ROBLOX,
players use core building components to create ela... 阅读全帖 |
|
T********Y
发帖数: 29 | 33 我是学OR的因为没有专门的版所以来这里发帖求助。。。
我们第一年prelim考optimization的教材是intro to linear and nonlinear
optimization, 辅助的是nonlinear programming.
书看的晕晕乎乎的，所以想刷点题做，不知道有没有类似的problem set或者student
manual solution 之类的。。
多谢~~~ |
|
G*****9
发帖数: 3225 | 34 数值问题， Mokhtar S. Bazaraa的那两本书比较好：LP&NLP
怪问题和tricks，Pardalos写的Global Optimization。
偏理论问题的， Andrzej Ruszczyński的Nonlinear Optimization
纯理论的， R. T Rockafellar的Convex Analysis
貌似OR是一个很小的领域，一共没有几本书的。 |
|
j*******e
发帖数: 586 | 35 can any optimization guru here give me some hints please? I don't know if my
question is just a trivial one in expert's eyes. But here it is:
my objective function f(x) is a scalar function of a vector x of length n. I
know that if x* is a solution, then cx* must also be a solution, where c is
a real constant. This actually reduces the n-dimensional problem to a n-1
dimension one. Is there any difference between the following two strategies:
(1) treat the problem as an unconstrained optimization |
|
X*****r
发帖数: 2521 | 36 【 以下文字转载自 Mathematics 讨论区 】
发信人: Xfilter (支持南开的兄弟们), 信区: Mathematics
标 题: 请问有那种optimization是解决变化的objective function的？
发信站: BBS 未名空间站 (Mon Jan 21 19:31:57 2008), 转信
就是objective function是time varying的
有没有那种optimization或者其他的数学model是deal这种time varying objective fu
nction的？
多谢多谢！ |
|
X*****r
发帖数: 2521 | 37 【 以下文字转载自 Mathematics 讨论区 】
发信人: Xfilter (大好河山美如画), 信区: Mathematics
标 题: 请问有什么optimization变量是matrix的？
发信站: BBS 未名空间站 (Wed Jul 30 22:47:52 2008), 转信
比如变量是一个psd matrix
有专门对付这种变量是一个matrix的optimization类型吗？
多谢指点！ |
|
m*******t
发帖数: 168 | 38 谢谢.
目前,我会一些单个的命令.但是,不会用matlab coding支解决一些稍微复杂一些的
optimization问题. 找了一些MATLAB的书,但是都不是关于optimization的.
里面
东西
ma |
|
l***7
发帖数: 3 | 39 我7月份刚从 MS of Environmental Engineering 毕业.
研究的方向是applying hydrology modeling, Statistics, optimization in water
resources area.
本人精通 SWAT, HEC-RAS.
MATLAB用的还不错, thesis就是用MATLAB来写的程序，主要有optimization (single/
multi-objective gentic algorithm), change of input, record output, result
comparison, uncertainty analysis, Statistics analysis.
恳求各位同学如果知道有任何相关工作机会的话，麻烦给我站内信。
谢谢大家了。 |
|
w****r
发帖数: 1046 | 40 You may take derivative with respect to xi to find your optimum f and g. But
the values of xi for the two optimization functions may differ.
Well, the optimum solution for maximizing the function of f(x)-g(x) probably
does not optimize f and g, simutaneously. Sometimes, it does.
Your problem is very similar to firm theory in microeconomics. |
|
b****t
发帖数: 114 | 41 Hi all,
I am solving a quasi-convex optimization problem, which is minimizing a
piecewise linear function (nonlinear indeed). The objective function is
quasi convex in it's domain. Can anyone suggest me some methods to solve
this type of problems? Any general methods can solve quasi-convex
optimization problems that have nice convergence properties?
Thanks a lot,
Beet |
|
x**h
发帖数: 173 | 42 I don't have optimization toolbox. Are they any ways to do global
optimization in matlab?
Thanks,
xyzh |
|
l*****a
发帖数: 119 | 43 paper要投 老板居然问我要投哪
老板说Mathematical Programming肯定没戏 SIAM on Optimization可以搏一下 但
是他也不敢保证能被接收 下面考虑一下二线Journal Optimization Methods
and Softwares ， Operations Research Letters， European Journal of
Operations Research, Linear Algebra and its applications. 老板问我想投哪
个 我也是第一次投论文 懂个鬼啊， 遂上来请教各位牛人。 对于我来说，当然
是希望journal越牛越好，还期待这篇论文能帮我申请到牛校的IEOR的PHD呢。 大牛说
说哪个二线journal看起来更“牛”。 |
|
A*******r
发帖数: 768 | 44 Linear algebra and its app. 文章太多，很水
SIAM 好像很慢
EJOR 个人觉得质量不高，欧洲运筹学会的会刊
其实我觉得重要的是quick review
这个很大程度要看你老板的分量了
paper要投 老板居然问我要投哪
老板说Mathematical Programming肯定没戏 SIAM on Optimization可以搏一下 但
是他也不敢保证能被接收 下面考虑一下二线Journal Optimization Methods
and Softwares ， Operations Research Letters， European Journal of
Operations Research, Linear Algebra and its applications. 老板问我想投哪
个 我也是第一次投论文 懂个鬼啊， 遂上来请教各位牛人。 对于我来说，当然
是希望journal越牛越好，还期待这篇论文能帮我申请到牛校的IEOR的PHD呢。 大牛说
说哪个二线journal看起来更“牛”。 |
|
m*******t
发帖数: 168 | 45 谢谢.
目前,我会一些单个的命令.但是,不会用matlab coding支解决一些稍微复杂一些的
optimization问题. 找了一些MATLAB的书,但是都不是关于optimization的. |
|
d*****1
发帖数: 1837 | 46 matlab optimization toolbox, but it kinda sucks.
find some third party optimization toolbox |
|
m******t
发帖数: 273 | 47 【 以下文字转载自 Statistics 讨论区 】
发信人: myregmit (myregmit), 信区: Statistics
标 题: solve an optimization model with integral as constraints
发信站: BBS 未名空间站 (Wed Mar 19 22:21:44 2014, 美东)
I need to solve a mathematical optimization model with integral as
constraints.
Min. | s1 - k1 | + | s2- k2 |
s.t.
integral_from_0_to_M of f(x) = 1
s1 = integral_from_0_to_M of x * f(x)
s2 = integral_from_0_to_M of x^2 * f(x)
M, k1 and k2 are positive numbers
f(x) is a proba... 阅读全帖 |
|
b*********e
发帖数: 38 | 48 not familiar with shortest path problem but just from what you wrote down,
you can convert to a standard quadratic optimization problem and any
optimization library could solve it.
_{ |
|
