Applied Mathematics

Hi I have a distribution for which I would like to use median say M. The problem is that I do not know how to define some range based on M+3 [math]\sigma[/math]. Is there some kind of variance related to median ?

Hi friends I am trying to construct a new number set which dosn't have the problem of division by zero and the square root of negative value so here is the basic All arithmitic rules and notions are the same as those of Reals set except the following statements 0^2=1 if a and b are positive reals and a*b=c then a * -b = c "if a>b" a * -b = -c "if a<=b" -a * -b = -c if a=b^n then Root(a) =b "without absolute value" The rest is the same as the traditional R set so as a result we have this solultions for old problems : SquareRoot(-1)=-1 " since -1 * -1 = -1 " 1/0 = 0 0^0 = 0^(1-1) = 0^1 * 0^-1 = 0 * 0=0 So is …

I'm trying to numerically integrate the function [math]f(x) = |x| + |x|^3, x\in[-1,1][/math] using Simpsons rule and analyse the error. I've been trying to analyse the rate of convergence of the error but can't seem to get anywhere. Experimentally I've got that it's about [math]O(J^-2)[/math] (I think) but I can't show it mathematically. I tried using the approach of splitting up the function into subintervals, then using the formula [math]|E_2,J| = \frac{-1}{2880} (b-a)h^4 |f^{(4)} (x)|[/math] but this fails as [math]|f^{(4)}(x)|\equiv 0, \forall x\in \Re^+ [/math] Any hints?

Since computers use binary numbers, how is it possible for them to display decimals? For instance, the following (C code) will print out 10, and not a binary representation of 10. int i = 10; printf(i); How is that done?

Here is a new angle for statistics and probability. It is an area that combines probability with logic. Here is the scenario; we have 100 dice with six sides. If you throw these dice, there are certain odds for a particular combination. No big deal. Say we randomly threw these 100 dice into a container that was just large enough to hold all the dice, like a drinking water glass. The number of possible combinations now becomes amplified, beyond expected, because some of the dice can now balance on edges and or apex points because they can be physically supported by other random landing of dice. To lower the odds back to what is expected, traditionally, for 100 dice, w…

Hello all, Well, this is my first post on this forum. I decided to find a forum like this since the questions I'm about to ask have been bugging me for some time now. Please note though, that I'm only 15 years old (just entered High School a month ago ) meaning that I'm probably missing something that may seem completely elementary to you University Professor's ;-) So excuse my ignorance Now, we all know that Pi is irrational, meaning that it can never be precise. That's also why we can never measure the exact circumference/area of a circle/sphere/whatever. My imagination is still a little limited, and my head usually hurts, when I try to think in 3D, so I'll sti…

Hi everybody,i need the articles below,can someone download them in full pdf for me please http://www.springerlink.com/content/l22658l7m5081vq0/ http://www.informaworld.com/smpp/con...0140201~db=all http://www.springerlink.com/content/n07u810uw2012457/ http://www.springerlink.com/content/1g29773423704201/ http://www.journals.uchicago.edu/doi/abs/10.1086/322831

Anyone here know anything about the Box-Wilson method of Statistical design and optimization of experiments? I have a few questions about finding the path of steepest ascent.

Can someone please tell me how to work out standard deviation.

hi everybody i am a new member in this forum. i need some good references about response surface method- D-optimal design for design of experiments. if you have please send to my E-mail. thanks.

I understand that if you use the "has a polynomial time certificate" definition of NP, that the complement of the Hamiltonian path problem does not appear to be in NP - there is no certificate of polynomial size that a DTM could use to verify whether a given graph has no such paths. But, using the alternative definition of NP, which is those problems that can be solved in polynomial time by an NTM, doesn't it appear that coHAMPATH is in NP? My "proof" would go like this: 1. Give the NTM the description of the entire graph. 2. The NTM then nondeterministically checks every possible path to see if it is Hamiltonian. If any of the branches accept, then reject. If none o…

Hallo everybody, We are developing a new product (Electrical motor assembled with Gear set for the material handling applications). We finished the modeling, and we just want to test the product physically with experiments. In this situations, we found that we have so many influencing parameters in the test, which will explode the number of experiments. And Moreover its difficult to interperate the correlations between each and every parameteres from the results. In this case, I want to do a step wise procedure to get a optimal design for the experiments. If anybody , having some sort of worked out examples or guiding links to do a step wise DoE, Please hel…

Does anyone know of any free software that is good at fitting curves to data? I have tried Mathematica, but it does not seem to do the job I need as the curve is highly non-polynomial. I should also add that such data analysis is outside my normal work and this is a favour for someone.

Hi All, I really need to understand laplace transform as i have an assignment on it. Its really confusing for me can anyone assist me on the following questions. Please help me to understand s^4 – 6s^3 + 18s^2 / 3s^6 ac + bs / s^2 + a^2 s + 5 / s2 - 6s + 25 and a differential equation using laplace tranform f'(t) + f(t) = e^-t, f(0) = 0 Thank you very much

Dear members I am a medical doctor starting a course in biostatistics, do you know where can I find very basic concepts of statistics? I am struggling to understand concepts of statistics, so I need to start from the beginning but I don't know any web page. I would need to understand the very basics in order to understand the basic books Any ideas? Thank you very much DrO

I'm doing a little project at the moment to do with how triangles relate to tetrahedrons and I have some interesting results which have allowed me to calculate what the 4D version would look like. I Made a simple model to test and it worked out right. The only problem now is that none of the shapes I've found have names as far as I know. Is there a name for a 4D shape made from 5 tetrahedrons? It also has 10 faces and 10 edges if that helps. Theres a 5D shape too consisting of 15 tetrahedrons (or 6 of the 4D shapes). Thanks if anyone knows.

I met a problem about finding the optimization of some function. I used the Trust-Region Newton and Quasi-Newton methods for the problem; however, with different initial guesses I sometimes got the local minimums. May I ask how to get out the trap of the local minimums please? I may try the Radom Walk method but it seems not be a good one. Any other ideas please reply! Thanks a lot!

I'm working on a homework assignment here, but I'm not actually looking for an answer to the problem, just a little help understanding which approach to take. My team is tasked with building a detailed sampling plan, but we're arguing about which approach to use. I was hoping I could get some insight as to why one method is better than the other for this situation. We've narrowed it down to either stratified or cluster sampling, but there is a debate within my team as to whether our data sets are homogeneous or heterogeneous. In our population we have thousands of students staying in various university dormitories, and we want to determine how long they remain re…

Dear members, does anyone know a reference to a paper where it is explained in details how to numerically solve non-linear Boltzmann equation with non-zero collision integral (hard sphere case) I also interested in solving numerically conservative Euler equations. Any paper or link to a numeric scheme descriptions would be greatly appreciated! Thank you very much! A.P.

I've got a question about how to do statistical analyses: Let's say a randomized controlled study of the efficacy of a new antiretroviral agent to be used in treating HIV/AIDS --specifically, the one here: http://www.scienceforums.net/forum/showthread.php?t=32796 -- is commenced in HIV+ mice, w/ 20 mice randomly assigned to the treatment group, and 20 mice randomly assigned to the placebo group. 18 mice in the treatment group end up w/ viral loads < 50 copies/ml --which is definied in the literature as clinically insignificant--, and a CD4+ T-cell count of > 500 cells/ul, which is that of a healthy individual --the remaning two succumbed from causes unrelated to…

I am not trying to undermine the practical usefulness of statistics, when used properly by a trained mathematician. But from the practical point of view of the lay person, a statistical approach can get irrational, since it can be used to manipulate a reasonable lay person. Let me give an example. Say eating X, doubles the risk of a person getting condition Y. The math expert has a good handle on this in terms of the hard numbers. It can tell the difference between going from 1 to 2 in a million and 100-1000 in a million. But the layperson is pitched "double the risk", for the 1 to 2 in a million. They are not experts so they then depend on others to interpret this …

Let X,Y be topological spaces. Consider Z = X x Y and the product topology genearted by the projections p_x, p_y. Let A be a subset of Z. Suppose that X,Y are locally path connected. Show that A is connected if and only if A is path connected.

You and your beloved have a pizza and a cheesecake for dinner. You love him or her but things must be fair! Prove that there are at least one ways to cut the pizza and the cheesecake in halves of equal areas by one straight cut. (By pizzas and cheesecakes, we mean compact connected subsets of R^2) let me give you some idea: the area is continuous change with respectively to x. the pizza is bounded by rectangle. move the line to another position called x bar. the area between two position change little bit. prove that the given area is less than epsilon. if M*delta x < epsilon. please help

I have collected 53000 data samples, and I want to found out how they are distributed i.e. normal distribution, laplace distribution etc. Is there a general way of determining this?

In memory of Arthur C. Clarke's recent death, I would like to post his excellent program on fractals. He considers them one of the most beautiful and remarkable discoveries in the entire history of mathematics: http://video.google.com/videoplay?docid=8570098277666323857 This program explores the far-reaching implications that fractals have both in mathematics and in our daily lives, and interviews a number of highly reputed mathematicians about the nature of fractals and the immense applications they could have in our daily lives. It feels a bit dated now, but still... excellent!