Displaying 20 results from an estimated 20000 matches similar to: "Error propagation"
2010 Sep 09
5
Calculating with tolerances (error propagation)
Hello Bernardo,
---------
If I understood your problem this script solve your problem:
q<-0.15 + c(-.1,0,.1)
h<-10 + c(-.1,0,.1)
5*q*h
[1] 2.475 7.500 12.625
---------
OK, this solves the simple example.
But what if the example is not that simple. E.g.
P = 5 * q/h
Here, to get the maximum tolerances for P, we need to divide the maximum
value for q by the minimum value for h, and
2008 Mar 25
1
Error propagation
Dear R-helpers,
I´m in the context of writing a general function for error propagation
in R.
There are somehow a few questions I would like to ask (discuss), as my
statistical knowledge is somewhat restricted.
Below is the function I wrote, the questions are marked.
Many thanks in advance.
propagate <- function(expr, varList, type = c("stat", "raw"), cov =
TRUE)
{
2013 Dec 11
2
[LLVMdev] Float undef value propagation
You are right some cases would definitely not be right like undef + Nan -> undef. For 2.0f case I'm not sure either if any bits could be known.
It seems that in general fadd( float undef, float %1) -> float %1 should always be safe and I just checked with latest code this doesn't happen.
Do you think the right solution would be to add such optimization? Is there any reason why we
2017 Jun 15
2
LLC does not do proper copy propagation (or copy coalescing)
Hello.
Could you please tell me how can I optimize with the back end (llc) the following
piece of assembly code generated by llc:
// NOTE: my processor accepts loops in the form of REPEAT(num_times)..END_REPEAT
R0 = ...
REPEAT(256)
R5 = R0; // basically unnecessary reg. copy
REPEAT(256)
R10 = LS[R4];
R2 = LS[R5];
R4 =
2001 Aug 28
1
Subsetting simulation output
Does anyone understand this?
I have a long vector parlist containing values of 138 parameters in 100
simulations.
The factor parno is defined by
trys <- 100
sim <- gl(trys,138)
parno <- gl(138,1,trys*138)
I want to extract and compare results for related groups of parameters but I
get inconsistent results:
> length(parlist[parno==37:42])
[1] 600
>
2013 Mar 08
4
Substitute value
Hi,
I have a large data frame and within this there is one column which contains
individual codes (eg. 1.1234.2a.2). I am splitting these codes into their 4
components using strsplit (eg. "1", "1234", "2a", "2"). However there are
some individual codes which do not have a last component (eg. 2.4356.3b. ),
I want to give these codes a "1" as their
2004 Aug 25
1
brlr function
Hi,
I'm trying the brlr function in a penalized logistic regression function.
However, I am not sure why I am encountering errors. I hope to seek
your advice here. (output below)
Thank you! Your help is truly appreciated.
Min-Han
#No error here, the glm seems to work fine
>
2008 Jul 14
2
Backslash in sub pattern?
Dear guRus,
I am trying to replace "~" by "$\sim$" for TeX. However, I can't get the
backslash to work. I would like to turn "DV~IV" into "DV$\sim$IV".
sub("~","$\sim$","DV~IV") => "DV$sim$IV"
sub("~","$\\sim$","DV~IV") => "DV$sim$IV"
2013 Jun 25
1
[LLVMdev] ldexp constant propagation
Hi,
I have the C program below, which contains a mathematical expression.
C code:
======
void ControlledRotationPiMinus(int target, int control, int j)
{
ControlledPhase(target,control,-PI/(2*pow(2,j)));
}
int main() {
..
int b = 3;
for (int j=1; j < b; j++)
ControlledRotationPiMinus(target, control, j);
..
}
Here is what I am doing: The function ControlledRotationPiMinus is called
2012 Apr 12
2
[LLVMdev] Question::ARM simulation and cross compilation.
Hello,
I'm trying to evaluate the performance improvement of instruction scheduling on one of the inorder ARM processor, I was looking for ARM simulator and I found two (Simplescalar/ARM and SimIt-ARM)
The code generated using llvm-2.9 and llvm-gcc and gcc 3.2.
I used these command :
$ llvm-gcc -O3 -o test1.bc -c --emit-llvm test1.c
$ llc -O3 -o test1.s -march=arm test1.bc -mcpu=strongarm110
2010 Oct 20
3
Plot help
Dear List,
I am relatively new to R and am trying to create more attractive plots than excel can manage!
I have looked through the various programmes ggplot, lattice, hmisc etc but my case seems to be not metnioned, maybe it is but i have not noticed - if this is the case i apologise.
2009 Jul 15
1
Simulation code error
Dear List,
I have some problem with my simulation code. Here is output from R:
> sim.sp <- function(data,CM,n,N)
+ {
+ C <- matrix(rep(NA,N),ncol=1)
+ for(i in 1:N)
+ {
+ j <- n
+ xx <- which(colSums(CM[j,])==1)
+ V <- names(xx)
+ V <- paste(V, collapse="+")
+ V <- paste("SBA~", V)
+ rd <- round(nrow(data)*(2/3))
+ d <-
2013 Dec 10
0
[LLVMdev] Float undef value propagation
On 12/9/13 2:13 PM, Raoux, Thomas F wrote:
>
> Constant propagation pass generates constant expression when undef is
> used in float instructions instead of propagating the undef value.
>
> ; Function Attrs: nounwind
>
> define float @_Z1fv() #0 {
>
> entry:
>
> %add = fadd fast float undef, 2.000000e+00
>
> ret float %add
>
> }
>
> Becomes:
2005 Apr 13
1
i param in "for" loop does not takes zeros?
Hi all
Is there any reason why the parameter i in a "for" loop ignores a value of
zero? For example
sim=c()
p=.2
for(i in 0:5)
{sim[i]=dbinom(i,5,p)
}
sim
[1] 0.40960 0.20480 0.05120 0.00640 0.00032
In this example the quantile i= 0 was ignored since
dbinom(0,5,p)
[1] 0.32768
The same behaviour occurs if I use a while loop to perform the same
calculation:
sim=c()
p=.2
i=0
2023 Feb 23
2
Possible NA Propagation Failure in RISC-V64 CPU?
Hi all,
I am currently compiling R to RISC-V64 CPU and I think I have discovered a
NA propagation failure.
How R implements NA (not available) and NaN (not-a-number) is explained in
detail here:
https://stat.ethz.ch/pipermail/r-devel/2014-February/068380.html.
In short, according to my understanding of R's convention, any calculation
involving NA but no NaN should result in NA (called NA
2019 May 15
1
domain still running although snapshot-file is deleted !?!
Hi,
i have a strange situation:
A domain is still running where domblklist points to a snapshot file and also dumpxml says the current drive is that snapshot file.
But the file has been deleted hours ago. And the domain is still running. I can login via ssh, the database and the webserver are still running,
domain is performant.
How can that be ?
Also lsof shows that the file is deleted:
2006 Jan 13
1
Variance-covariance by factor
Dear all,
I have a data frame with one factor and four numeric variables and
wish to obtain the var-cor matrix separately by factor. I tried by() and
sapply() but getting nowhere. I understand this can be done by subsetting
the dataframe, but there should have some sleek ways of doing it.
Here is a simulated dataframe;
s <- rep(c("A","B","C"), c(25,22,18))
d
2006 Sep 20
4
Calculating mean together with split
Hi
I have a table called npl containing results of simulations.
It contains about 19000 entries and the structure looks like this:
NoPlants sim run year DensPlants
1 6 lng_cs99_renosterbos 1 4 0.00192
.
.
.
it has 43 different entries for sim and year goes from 1 to 100, and run
from 1 to 5.
I would like to calculate the mean of DensPlants for each
2013 Dec 09
4
[LLVMdev] Float undef value propagation
Constant propagation pass generates constant expression when undef is used in float instructions instead of propagating the undef value.
; Function Attrs: nounwind
define float @_Z1fv() #0 {
entry:
%add = fadd fast float undef, 2.000000e+00
ret float %add
}
Becomes:
; Function Attrs: nounwind
define float @_Z1fv() #0 {
entry:
ret float fadd (float undef, float 2.000000e+00)
}
Is it safe
2008 Mar 05
2
simulating the anova
I have been trying to figure out how to run a simple simulation of the ANOVA
and I'm coming up just a bit short. The code I've got is:
cohen.f = .25
groups = 4
between.var = 19
within.var = between.var / cohen.f ^ 2
n = 500
sim.means = rnorm(n = groups, mean = 0, sd = sqrt(between.var))
sim.data = lapply(sim.means, function(mean) rnorm(n = n, mean = mean, sd =
sqrt(within.var)))