search for: roundoff

Displaying 14 results from an estimated 14 matches for "roundoff".

2011 Apr 24
2
random roundoff?
...e0] or nearby, I do: cerr << "some stuff" << endl; mat3 = matmult(mat1,mat2); I get a difference of the order 1.0e-15 depending on whether the cerr line does or does not end in "endl" as shown. I am imagining that there is some "randomness" in the roundoff that depends on the I/O situation. Is this credible? Any other suggestions? Thanks for your help, Mike.
2012 Sep 25
1
how to pass a function to a function inside a function
....tol), as.double(rel.tol), limit = limit, PACKAGE = "base") } res <- wk[c("value", "abs.error", "subdivisions")] res$message <- switch(wk$ierr + 1, "OK", "maximum number of subdivisions reached", "roundoff error was detected", "extremely bad integrand behaviour", "roundoff error is detected in the extrapolation table", "the integral is probably divergent", "the input is invalid") if (wk$ierr == 6 || (wk$ierr > 0 && stop.on.er...
2012 Jan 10
1
Lapack routine dgesv: system is exactly singular
Hi I have a problem with this error, I have searched the archives and found previous discussion about this, can I cannot understand how the explanations apply to what I am trying to do. I am trying to do Log_rank Survival analysis, I have included tables and str command, is it a factor/integer problem? If so how do I correct this, as all my attempt to recode the data have failed.
2007 Jun 29
1
Comparison: glm() vs. bigglm()
Hi, Until now, I thought that the results of glm() and bigglm() would coincide. Probably a naive assumption? Anyways, I've been using bigglm() on some datasets I have available. One of the sets has >15M observations. I have 3 continuous predictors (A, B, C) and a binary outcome (Y). And tried the following: m1 <- bigglm(Y~A+B+C, family=binomial(), data=dataset1, chunksize=10e6)
2002 Jan 07
0
New package: colSums
...'s not NA or NaN if x==x), which works really great for me, but may not be portable. If it doesn''t work for you, try modifying the #define line in colSums.c. I would like to hear about platforms where this fails. - colVars is very naive, e.g. I''m probably exacerbating roundoff error when mu >> sigma. I personally don''t worry because in finance, mu (return) is never >> sigma (risk) :-). The S-Plus documentation for colVars claims they do something fancy with the "two-pass method described in Chan, Golub, and LeVeque (1983)" that I...
2004 Jun 01
0
qhull in R?
...hulls, Delaunay triangulations, halfspace intersections about a point, Voronoi diagrams, furthest-site Delaunay triangulations, and furthest-site Voronoi diagrams. It runs in 2-d, 3-d, 4-d, and higher dimensions. It implements the Quickhull algorithm for computing the convex hull. Qhull handles roundoff errors from floating point arithmetic. It computes volumes, surface areas, and approximations to the convex hull." Thanks Agus PLEASE NOTE NEW E-MAIL ADDRESS Dr. Agustin Lobo Instituto de Ciencias de la Tierra (CSIC) Lluis Sole Sabaris s/n 08028 Barcelona SPAIN tel 34 93409 5410 fax 3...
2010 Jun 02
0
[LLVMdev] Generating Floating point constants
On Jun 2, 2010, at 3:28 AMPDT, Stéphane Letz wrote: > > Le 2 juin 2010 à 12:21, Eli Friedman a écrit : > >> On Wed, Jun 2, 2010 at 2:59 AM, Stéphane Letz <letz at free.fr> wrote: >>> Hi, >>> >>> We need to generate "Floating point constants" in our code. In http://llvm.org/docs/LangRef.html it is explained that FP has to
2008 Apr 09
2
GLM fitting in R and Statistica
Hi, I have a problem concerning discrepances between R (which I use) and Statistica (which uses my supervisor). I can't say what is the origin of these differences but unfortunately my supervisor doesn't know that either. Our response variable is number (or presence/absence) of parasites in rodents and explanatory variables are presence/absence of several alleles. The rodents
2010 Jun 02
3
[LLVMdev] Generating Floating point constants
Le 2 juin 2010 à 12:21, Eli Friedman a écrit : > On Wed, Jun 2, 2010 at 2:59 AM, Stéphane Letz <letz at free.fr> wrote: >> Hi, >> >> We need to generate "Floating point constants" in our code. In http://llvm.org/docs/LangRef.html it is explained that FP has to follow special encoding rules to be handled by LLVM later one (hexadecimal
2008 Mar 31
5
[LLVMdev] Additional Optimization I'm Missing?
Hello, I'm working on using the LLVM JIT for a little project of mine, amazing work first off! I have a question about optimization passes. I initially have this function I've created, in python it looks like this: OS_end = 50OS_start = 0OS_timestep = 1birth_rate = .3population = 30.0for time in range(OS_start, OS_end, OS_timestep): births = birth_rate * population deaths = 0.1
2008 Aug 01
5
drop1() seems to give unexpected results compare to anova()
Dear all, I have been trying to investigate the behaviour of different weights in weighted regression for a dataset with lots of missing data. As a start I simulated some data using the following: library(MASS) N <- 200 sigma <- matrix(c(1, .5, .5, 1), nrow = 2) sim.set <- as.data.frame(mvrnorm(N, c(0, 0), sigma)) colnames(sim.set) <- c('x1', 'x2') # x1 & x2 are
2002 Jan 07
3
tool for listening tests
I've been looking around for a tool to compare the quality of different audio files, didn't find anything, and so botched together something over the past few days: http://www.btinternet.com/~jfchapman/files/mcp.zip (Win32, 266Kb) It's just a small tool for playing up to 3 files simultaneously, with the ability to switch between the outputs to compare the sound
2001 Mar 21
3
bitrtate peeling and lossless compression
I just read some of the discussion on the list about 'bitrate peeling' and remembered an interview of Monty that I have read recently. In it he says that Vorbis uses MCDTs <sp> and that these are theoretically reversable. And now, I learn that theoretically we can use bitrate peeling to make smaller files from larger ones, and that leads to my question. Could I theoretically
2009 Sep 22
5
Indexing Ogg files for faster seeking
I've developed an indexer which embeds a keyframe index track in Ogg files. It embeds the index in its own track, so that players that don't understand or don't want to use the index can just ignore it. Ogg needs this to make seeking over networks faster and more efficient. Currently we must do a bisection search when seeking, which usually takes aound 6 HTTP requests, give or