Displaying 20 results from an estimated 5000 matches similar to: "Differential Equations"
2006 Jan 19
1
empirical maximum likelihood estimation
Dear R-users
Problem:
Given the following system of ordinary differential euqations
dM/dt = (-n)*M-h*M
dS/dt = n*M-h*S+u*R
dA/dt = h*S-q*A
dI/dt = q*A-p*I
dJ/dt = h*M-v*J
dR/dt=p*I+v*J-u*R
where M,S,A,I,J,R are state variables and n,h,u,q,p,v parameters.
I'm able to calculate the likelihood value based on the solutions
M,S,A,I,J,R of the ODE's given the data, but without an explicit
2004 Jun 08
1
Differential Equations
Hello!
I would like to know if R can solve Differential Equations...
I don't think so because, in my point, I see R like a Statistical System, not a
Math System. Am I wrong?
Thank you very much.
M??rcio de Medeiros Ribeiro
Graduando em Ci??ncia da Computa????o
Departamento de Tecnologia da Informa????o - TCI
Universidade Federal de Alagoas - UFAL
Macei?? - Alagoas - Brasil
Projeto CoCADa
2006 Nov 29
2
How to solve differential equations with a delay (time lag)?
Hi,
I would like to solve a system of coupled ordinary differential equations,
where there is a delay (time lag) term. I would like to use the "lsoda"
function "odesolve" package. However, I am not sure how to specify the
delay term using the syntax allowed by odesolve.
Here is an example of the kind of problem that I am trying to solve:
> library(odesolve)
2001 Sep 11
2
Differential Equations Using R?
To whom it may concern,
I am a student at Macaleste College, and next semester Macalester
is going to offer a course for CellBio that is mainly statistically based.
For the most part the students will be using R for analysis. The problem is
there will be some simple differential equations for the students to solve.
The committee that in charge of the classes corriculam would like only to
2000 Nov 17
1
Ordinary differential equations in R?
Is there any R code available for solving ODE's? I am considering building
an interface to ODEPACK, but don't want to duplicate any existing effort.
--
Tom Wainwright
NOAA/NMFS/NWFSC
2030 S Marine Science Dr
Newport, OR 97365 USA
thomas.wainwright at noaa.gov
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read
2000 Jul 26
4
differential equations
Hi, Does somebody knows of the existence of a library of functions
for solving differential equations, I need a solver for a system of non
linear first order differential equations. I think there was something
in IMSL but that was a long time ago and probably there are some
new algorithms in the new now.
Thanks for any pointers.
.
R. Heberto Ghezzo Ph.D.
Meakins-Christie Labs
McGill
2007 Apr 09
1
How to solve differential and integral equation using R?
Hello,
I want to know if there are some functions or packages to solve differential
and integral equation using R.
Thanks.
Shao chunxuan.
[[alternative HTML version deleted]]
2006 Jun 12
2
solving first-order differential equation
I am an initial user of R. Could you give me some explanations or examples on how to solve the first order differential equations by the first-order Runge-Kutta method?
Thank you very much
Kind regards
2012 Dec 05
2
stiff delay differential equations
Hello List,
Can you recommend me if odeSolve can handle stiff delay differential equations
with discontinuities? Or any other package?
Best,
-m
2008 Feb 15
1
How to estimate the parameters of differential equations from data
Hello list
I have a theoretical differential equation model (two coupled differential
equations) describing the acidification of dairy cultures in milk:
dX/dt = f(H, param)*X
dH/dt = g(param)*dX/dt
pH = -log10(H)
I also have actual data of the same.
I would like to estimate the parameters of the theoretical model from real
data, but don't know how to go about it in R (I'm fairly new
2011 Jun 15
2
Trouble with compound functions---differential equations
Hi all,
My apologies if this message is incredibly inept but I am very new to both
computer programming and to R.
I am working with the odesolve add-on and have the following function
defined
RVF_Single <- function(t, x, p)
within the script I also have the following functions defined:
T1<-function(t) {T1<-27.5-12.5*cos(2*pi*t/365)}
and
B1<-function(T1,t)
2008 Aug 10
2
Differential Equations there use in R (population modeling)
e1 <- function(x,b,t){
d<-(x)*(b^t)
plot(d)
}
e1(2, 2,seq(from=0, to=6, by=1))
Is there a way to do this with a change in time. I would like to use
differential equations. I am trying to model
a population with an initial value, fecundity per time step, and a
death rate. The above simply shows an exponential growth rate. I
would like to model species response like the famous
2017 Jun 21
4
How to apply a system of ordinary differential equations to a cell grid?
Hello,
I am developing an agent-based model to simulate the spread of infectious diseases in heterogeneous landscapes composed of habitat polygons (or clumps of connected cells). To simplify the model, I consider a habitat grid (or raster) containing the polygon ID of each cell. In addition, I have epidemiological parameters associated with each polygon ID. At each time step, the parameter values
2013 Jan 03
1
R2OpenBUGS question with differential equations
Dear All,
Currently I am running the following code:
library(stats4)
library(odesolve)
library(rgenoud)
Input<-data.frame(SUB=c(1),time=c(0.5,3,10,15),lev=c(2.05,12.08,9.02,8))
XD<-500
IT<-3
diffeqfun<-function(time, y, parms) {
if(time<=IT)
dCpdt <- (XD/IT)/parms["Vol"] -
2008 Oct 13
1
Simulations using differential equations
Dear R-users,
I am trying to perform some simulations from a model defined by ordinary
differential equations. I would be grateful if someone could indicate some
functions/packages/examples I could look at.
Thank you in advance.
Sebastien
2017 Jul 17
0
How to apply a system of ordinary differential equations to a cell grid?
It seems that the method `iteration` in the function `ode` can be useful in my case:
> Method "iteration" is special in that here the function func should
> return the new value of the state variables rather than the rate of
> change. This can be used for individual based models, for difference
> equations, or in those cases where the integration is performed within
>
2017 Jun 21
0
How to apply a system of ordinary differential equations to a cell grid?
> On Jun 21, 2017, at 12:48 PM, Marine Regis <marine.regis at hotmail.fr> wrote:
>
> Hello,
>
> I am developing an agent-based model to simulate the spread of infectious diseases in heterogeneous landscapes composed of habitat polygons (or clumps of connected cells). To simplify the model, I consider a habitat grid (or raster) containing the polygon ID of each cell. In
2005 Oct 27
1
Fitting of Non-Linear Diff Equations and Parameter Estimation
Hello Everybody,
I am running R 2.2.0 with Windows XP
i am trying to fit nonlinear differential equation to data sets which looks
like this:
Week N C
0 1 1
1 5 6
2 6.2 12.2
3 59 71.2
4 39 110.2
5 38 148.2
6 44 192.2
7 20.4 212.6
8 19.4 232
9 34.2 266.2
10 35.4 301.6
and i need to fit these data to the following diff equation:
dNdt=a*N-b*N*C, dCdt=N^2,
Where a=birth rate, b=death rate and N=
2001 Dec 13
3
R-1.4.0: how to use getSymbolInfo()?
I have a package that solves systems of ordinary differential equations
coded as an R function (odesolve, on CRAN). The function is passed to R
code, and c and Fortran code called by it uses lang4() and eval() to
evaluate the R function inside a compiled c function to use in a
compiled ODE solver. This works quite well, but can be slow.
I'd like to be able to supply the name of a compiled
2007 Jun 06
3
Using odesolve to produce non-negative solutions
Hello,
I am using odesolve to simulate a group of people moving through time and transmitting infections to one another.
In Matlab, there is a NonNegative option which tells the Matlab solver to keep the vector elements of the ODE solution non-negative at all times. What is the right way to do this in R?
Thanks,
Jeremy
P.S., Below is a simplified version of the code I use to try to do this,