similar to: ruby to solve a physics question

Respected All, I hope you are enjoying good health, I am tring to write a program in R but could not be very sucessful. My program draws random sample form bivariate normal distribution and then compute a variable PIJ. For certian samples some entries of variable PIJ is apearing as negative, which result in negative variance estimator. I want to introduce a loop in my program that verify the each

hello R: we have a two-parameter IRT simulation code. The goal is to generate a response matrix.But the "for" part doesn't run. we don't know what is wrong with it. Thanks so much~~~ I <- 10 J <- 5 response <- matrix(0, 10, 5) pij <- function(a,b,theta) { a <- rnorm(J, 0.8, 0.04) a b <- rnorm(J, 0, 1) b theta <- rnorm(I, 0,1) theta for( i in 1:I ) { for(

Respected All, I am writing a program in R and facing some problem with applying "if statment". Program first draw random numbers from bivariate normal distribution then compute variable say Pi and Pij from that sample and then further computation ..... ..... ..... In some samples Pij is appearing with negitive sign and ultimately resulted in an negative variance estimator.

Hi Friends, I'm trying to model the consumer decisions (Click-Through Rate and Conversion) in Search Engine Advertising using a hierarchical Bayesian binary logit. The input data is the weekly CTRs and Avg. Position for each search keyword. CTR is modeled as (for each keyword i and week j): Pij = exp(C + Bi x Positionij + A1 x Lengthi + A2 x Brandi + A3 x ProductSpecifici) / [1 + exp(C +

Hi there, I'm new to R but I thought this is the most likely place I could get advice or hints w.r.t the following problem: I have a series of measurements xi with associated uncertainties dxi. I would like to construct the probability density histogram of this data where each density estimate has an associated error that is derived from the dxi. In other words, for large dxi the

Dear all, Is there a function in R that checks transitivity and acyclicity of a given nXn matrix with entries representing a decision-maker's comparisons of n objects? Like 0 1 0 1 1 1 0 0 0 1 0 0 1 0 0 0 1 1 0 0 1 0 0 0 0 1 0 1 0 1 0 1 0 1 0 0 1 represents xPy and 0 represents ~xPy. Is there a vectorized solution to this? n can be quite large. Thanks in advance, Alex

Yes unfortunately I do not have much luck recieving help from the SAMBA mailing list. After much playing I found something weird that was seemingly causing incorrect comments. Most printers would recieve the comment - "no entries" which originally I assumed to be the default comment given by Win95 when it could not get a proper comment. However I later found that this is not the case.

I have developed a GAM model in order to predict Y using 4 X variables. 2 of these X's are factors, and 1 is a spline. Part of the data looks like: Days WRM variety PWM O_EC 31 75 1 90 234 31 79 1 78 283 31 82 1 92 281 31 84 1 96 213 31 99 2 69 247 31 100 2 77 324 31 104 2 74 259 31 118 2 81 282 31 61 3 58 478 31 98 3 83 429 31 98 3 70 379 31 156 3 87 467 31 78 4 56 283 31 97 4 67 282 31

[this message needed manual improvement by the mailing list administrator since it was `HTMLified' .. ``please do not''] Apologies for bothering you about a fairly trivial matter. I have been getting some inconsistencies with the display digits in R V1.5. I have been using the hypergeometric distribution function, and have found that when printing out the results from this

Hershey Felder, The Secrets About Musical Instruments And Physics Every sound produced by a musical instrument has a physical explication, the way instruments are created and the type of materials that are used define in a unique way the resulting sound. The sound wave is a transfer of energy that doesn't imply matter. Within a more theoretical approach sounds are Mechanical Longitudinal

Dear All, A new task view "ChemPhys" on chemometrics and computational physics is available on CRAN (http://cran.r-project.org/web/views/ChemPhys.html). It describes packages and functions that are of use in modeling chemical/physical systems. Suggestions and comments regarding this task view are welcome. If you think a new category, package or function should be added, please mail.

Hello, Erwin > So if you port this SSE code to another platform (Linux, Altivec, > NEON), you could contribute it back to Bullet? I believe this should work as-is on linux. Am I missing something? > optimizations, but haven't contributed this back. > This NEON/VFP, part of the an open source iPhone project, could be a > starting point for this: > http://tinyurl.com/y9gv3e8

Hello, Everyone > Sounds like a very interesting SSE test. I'm working on it. Hopefully it will be added today or tomorrow to LLVM testsuite. -- With best regards, Anton Korobeynikov Faculty of Mathematics and Mechanics, Saint Petersburg State University

Hello, Erwin > I suggest working on a better benchmark that tests independent parts of the > pipeline, > so we don't accumulate results (several frames) but we test a single > algorithm at a time, > with known input and expected output. This avoid unstability and we can > measure the error of the output. > Anton, are you interested in working together on such improved

On Tuesday 05 January 2010 15:57, Dan Gohman wrote: > On Jan 5, 2010, at 1:38 PM, David Greene wrote: > > I don't think there's a flag that says "don't do anything risky, > > ever." > > "Don't do anything risky with floating-point" is the default mode. If > you're aware of any unsafe floating-point optimizations being done by >

We haven't determined what 'failing' means or what the 'correct' behaviour is. Imagine a ball at the top of a rounded hill. If the ball is not exactly at the top but a tiny amount on the left it will roll left, but a tiny amount on the right it will roll right. The difference in initial position can be negligible but the final result is miles away. Is there a irc channel or

Hi. I was wondering if anyone has compiled Bullet Physics for WindRiver's vxWorks (or know of anyone who may have done so). Any insight / info / help would be very much appreciated. Thanks! -Ryan (aka keppy) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20100120/53f5b439/attachment.html>

While browsing about, found http://www.voip-info.org/wiki/view/TDM400P, where I found this comment: "Here's a tip passed on from an old telephone engineer. Where your copper 2-wire cable approaches the building, underground, finish with several large loops, about a metre in diameter, laid on top of each other. Fast moving, high energy spikes will spin off the outside of the loop as they

On Dec 15, 2009, at 5:15 PM, Erwin Coumans wrote: > The linux builds are not using SSE right now, but the vector data is > 16-byte aligned on all platforms. > So if you port this SSE code to another platform (Linux, Altivec, > NEON), you could contribute it back to Bullet? > The most interesting SSE part is the innerloop of the constraint > solver: http://tinyurl.com/ydoapct

On Jan 5, 2010, at 1:38 PM, David Greene wrote: > I don't think there's a flag that says "don't do anything risky, > ever." "Don't do anything risky with floating-point" is the default mode. If you're aware of any unsafe floating-point optimizations being done by default, please file a bug. > For example, a gfortran-fronted LLVM should have a way