Displaying 20 results from an estimated 333 matches for "quadratic".

2008 Oct 22

1

Spatstat help - quadratcount query

Hi all,
I am using quadratcount in spatstat to divide a window containing a
point pattern into a grid of quadrats containing the intensity of points
in each quadrat. My data is in UTM co-ordinates. My window is defined
as follows:
>p15<-ppp(x,y,window=owin(c(341710,342100),c(3126465,3126780)),marks=NUL
L, checks=TRUE)
Giving me a distance of 390m in the 'x' direction and 315m in

2005 Dec 05

2

lmer and glmmPQL

I have been looking into both of these approaches to conducting a GLMM,
and want to make sure I understand model specification in each. In
particular - after looking at Bates' Rnews article and searching through
the help archives, I am unclear on the specification of nested factors
in lmer. Do the following statements specify the same mode within each
approach?
m1 = glmmPQL(RICH ~ ZONE,

2016 Dec 18

2

llvm (the middle-end) is getting slower, December edition

>
>
>>
> LVI is one of those analyses with quadratic runtime, but has a cutoff to
> its search depth so that it is technically not quadratic. So increased
> inlining could easily exacerbate it more than non-"quadratic" passes.
> (increased inlining would also cause a general slowdown too).
>
>
LVI is only quadratic because of...

2004 Oct 06

0

quadratically constrained quadratic programming

Hi,
Does anybody have experience to solve an quadratic programming problem
with quadratic constraints in R?
It seems that the package "quadprog" only handles the quadratic
programming with linear constraint. My probelm is to maximze
x^T\Sigma_{xy} y,
subject to x^Tx=1, y^T\Sigma_{yy} y=1, and sum(y)<t, or sum(y)=t, where
x and y are t...

2005 Mar 26

1

lme: random effects of a quadratic term

Hello,
I am estimating the following model:
so2.lme<-lme(so2~1+I(alcadakm^2)+dia,data=subjectes2,na.action=na.omit)
And when I try to plot the random effects of the quadratic term with
respect to a covariate (mam) I get an error:
> so2.lmeRE<-ranef(so2.lme,augFrame=T)
> plot(so2.lmeRE,form=I(alcadakm^2)~mam)
Error in plot.ranef.lme(so2.lmeRE, form = I(alcadakm^2) ~ mam ) :
Only single effects allowed in left side of form.
Any suggestion?
Thanks!
Montse Ru...

2016 Dec 18

0

llvm (the middle-end) is getting slower, December edition

On Sat, Dec 17, 2016 at 8:39 PM, Daniel Berlin <dberlin at dberlin.org> wrote:
>
>>>
>> LVI is one of those analyses with quadratic runtime, but has a cutoff to
>> its search depth so that it is technically not quadratic. So increased
>> inlining could easily exacerbate it more than non-"quadratic" passes.
>> (increased inlining would also cause a general slowdown too).
>>
>>
> LVI is...

2017 Jul 13

3

How to formulate quadratic function with interaction terms for the PLS fitting model?

I have two ideas about it.
1-
i) Entering variables in quadratic form is done with the command I
(variable ^ 2) -
plsr (octane ~ NIR + I (nir ^ 2), ncomp = 10, data = gasTrain, validation =
"LOO"
You could also use a new variable NIR_sq <- (NIR) ^ 2
ii) To insert a square variable, use syntax I (x ^ 2) - it is very
important to insert I before the...

2010 Dec 04

1

Quadratic programming with semi-definite matrix

Hello.
I'm trying to solve a quadratic programming problem of the form min
||Hx - y||^2 s.t. x >= 0 and x <= t using solve.QP in the quadprog
package but I'm having problems with Dmat not being positive definite,
which is kinda okay since I expect it to be numerically semi-definite
in most cases. As far as I'm aware the pr...

2009 Mar 28

1

Quadrat Variance analysis

Is there any package or operation in R designed to conduct or facilitate
Quadrat Variance analysis of spatial data? Any leads would be much
appreciated as I have found very little in my searches thus far.
Tyler
--
View this message in context: http://www.nabble.com/Quadrat-Variance-analysis-tp22752517p22752517.html
Sent from the R help mailing list archive at Nabble.com.

2017 Jul 13

0

How to formulate quadratic function with interaction terms for the PLS fitting model?

Below.
-- Bert
Bert Gunter
On Thu, Jul 13, 2017 at 3:07 AM, Luigi Biagini <luigi.biagini at gmail.com> wrote:
> I have two ideas about it.
>
> 1-
> i) Entering variables in quadratic form is done with the command I
> (variable ^ 2) -
> plsr (octane ~ NIR + I (nir ^ 2), ncomp = 10, data = gasTrain, validation =
> "LOO"
> You could also use a new variable NIR_sq <- (NIR) ^ 2
>
> ii) To insert a square variable, use syntax I (x ^ 2) - it is very
>...

2013 May 05

1

slope coefficient of a quadratic regression bootstrap

Hello,
I want to know if two quadratic regressions are significantly different.
I was advised to make the test using
step 1 bootstrapping both quadratic regressions and get their slope
coefficients.
(Let's call the slope coefficient *â*^1 and *â*^2)
step 2 use the slope difference *â*^1-*â*^2 and bootstrap the slope
coeffi...

2004 Jan 13

0

Running out of memory

I'm working with large data frames and running out of memory. I hope some
of you may be able to suggest a more efficient approach.
I have grid/lattice data representing a time series of 1 m2 quadrats in a
grassland: Each 1 cm2 cell or pixel contains one ecological state (ie grass
or bare ground). The goal is to calculate, for each cell, the transition
probabilities to all available

2017 Nov 28

0

Extract all point in a quadrats by spatstat package

Hi,
With the following code i can divides window into quadrats and counts the numbers of points in each quadrat.
library(spatstat)
X <- runifpoint(50)
quadratcount(X)
quadratcount(X, 4, 5)
quadratcount(X, xbreaks=c(0, 0.3, 1), ybreaks=c(0, 0.4, 0.8, 1))
qX <-? quadratcount(X, 4, 5)
plot(X)
plot(qX, add=TRUE)
But I want to mark each? quadrats? and select/ extract only those points by

2017 Jul 16

2

How to formulate quadratic function with interaction terms for the PLS fitting model?

...<bgunter.4567 at gmail.com> wrote:
>
> Below.
>
> -- Bert
> Bert Gunter
>
>
>
> On Thu, Jul 13, 2017 at 3:07 AM, Luigi Biagini <luigi.biagini at gmail.com> wrote:
>> I have two ideas about it.
>>
>> 1-
>> i) Entering variables in quadratic form is done with the command I
>> (variable ^ 2) -
>> plsr (octane ~ NIR + I (nir ^ 2), ncomp = 10, data = gasTrain, validation =
>> "LOO"
>> You could also use a new variable NIR_sq <- (NIR) ^ 2
>>
>> ii) To insert a square variable, use syntax I...

2017 Jul 16

0

How to formulate quadratic function with interaction terms for the PLS fitting model?

...if(20)
> mdl1 <-lm(y~df*I(df^2))
> mdl2 <-lm(y~df*poly(df,degree=2,raw=TRUE))
> length(coef(mdl1))
[1] 16
> length(coef(mdl2))
[1] 40
Explanation:
In mdl1, I(df^2) gives the squared values of the 3 columns of df. The
formula df*I(df^2) gives the 3 (linear) terms of df, the 3 pure
quadratics of I(df^2), the 9 cubic terms obtained by crossing these,
and the constant coefficient = 16 coefs.
In mdl2, the poly() expression gives 9 variiables: 3 linear, 3 pure
quadratic, 3 interactions (1.2, 1.3, 2.3) of these. The df*poly()
term would then give the 3 linear terms of df, the 9 terms of...

2011 Jan 21

0

Marginality rule between powers and interaction terms in lm()

Dear all,
I have a model with simple terms, quadratic effects, and interactions.
I am wondering what to do when a variable is involved in a significant
interaction and in a non-significant quadratic effect. Here is an
example
d = data.frame(a=runif(20), b=runif(20))
d$y = d$a + d$b^2
So I create both an simple effect of a and a quadratic effect o...

2009 Mar 27

0

Quadratic Discriminant Analysis (qda)

Hi listers,
Does anybody knows if the function qda for quadratic discriminant analysis
provides the coefficients of quadratic discriminants...
Well, I find out that for the linear discriminant analysis lda, the fonction
provides the coefficients...
Thanks in advance,
Marcio
--
View this message in context: http://www.nabble.com/Quadratic-Discrimina...

2017 Jul 13

2

Quadratic function with interaction terms for the PLS fitting model?

Dear all,
I am using the pls package of R to perform partial least square on a set of
multivariate data. Instead of fitting a linear model, I want to fit my
data with a quadratic function with interaction terms. But I am not sure
how. I will use an example to illustrate my problem:
Following the example in the PLS manual:
## Read data
data(gasoline)
gasTrain <- gasoline[1:50,]
## Perform PLS
gas1 <- plsr(octane ~ NIR, ncomp = 10, data = gasTrain, validation = &quo...

2012 Sep 24

2

Quadratic function-like call delay

Hi,
There is a quite annoying thing, don`t sure if I can call it a bug.
How to reproduce:
- start a bunch of VMs,
- stop libvirt,
- start libvirt and immediately issue any call, say, 'virsh version',
- delay until call completion may be fitted nearly as quadratic
function from number of running VMs, qemu-kvm in my case (see link
below). After this delay passed, any calls executed without slowdown,
so problem is only a 'dead gap' after restarting service.
http://xdel.ru/downloads/libvirt.png

2006 Jun 02

1

geoR, plot of variog4 lines incomplete

I'm using R for Mac OSX version 1.14 (2129) and the geoR package
version 1.6-5 (the current version in the R repository). I'm running
R in OS 10.4.6 on a Mac G4 iBook (933MHz, 640 MB DDR SDRAM). I
searched the R archive and did not find a posting on this issue.
I want to use the variog and variog4 functions of geoR to
characterize the pattern of spatial autocorrelation of tree