Displaying 20 results from an estimated 120 matches similar to: "solving ODE's in matrix form with lsoda()"
2018 Mar 23
3
Tripp-Lite BCPERS450 shutdown/restart problems
Thanks, Charles. I pulled your change and it fixed my segmentation
fault.
I discovered the following code at line 571 in usbhid-ups.c. This is
part of the "checking for alternatives" code:
if (!strcasecmp(cmdname, "shutdown.return")) {
int ret;
/* Ensure "ups.start.auto" is set to "yes", if supported */
if
2008 Jan 22
1
ODE's in R
Dear all,
Has anybody tried numerical solving of ODE's and/or transport equations
in R? (Don't ask how we ended up in using R for this job, in the first
place!)
More precisely, does anybody know any technical issue that could make
the work insecure in the sense of propagation of errors? Is there any
track of evidence that R is, in this kind of task, less reliable than
e.g. MatLab?
2005 Nov 06
1
Problem defining a system of odes as a C library with lsoda
I have been trying to make use of the odesolve library on my
university's Linux grid - currently R version 2.0.1 is installed and
the system runs 64-bit Scientific Linux based on Redhat. I cannot seem
to get lsoda working when I define the model as a shared C library. For
example, the following snippet uses the mymod.c example bundled with
the package:
### START
rm(list=ls())
2001 May 11
1
lsoda
I am running R 1.2.3 with ESS5.1.18 with Windows 98.
I am trying to use lsoda in the odesolve apckage and am having problems.
Question:
The return value of the function of the system of ode's has to be a list
that includes first, the ode's and second, "a vector
(possibly with a `names' attribute) of global values that are
required at each point in `times'."
I
2010 Apr 06
1
estimating the starting value within a ODE using nls and lsoda
All-
I am interested in estimating a parameter that is the starting value for an ODE model.
That is, in the typical combined fitting procedure using nls and lsoda (alternatively rk4), I first defined the ODE model:
minmod <- function(t, y, parms) {
G <- y[1]
X <- y[2]
with(as.list(parms),{
I_t <- approx(time, I.input, t)$y
dG <- -1*(p1 + X)*G +p1*G_b
dX <-
2005 Jul 27
4
odesolve/lsoda differences on Windows and Mac
Hi -
I am getting different results when I run the numerical integrator
function lsoda (odesolve package) on a Mac and a PC. I am trying to
simulating a system of 10 ODE's with two exogenous pulsed inputs to the
system, and have had reasonably good success with many model parameter
sets. Under some parameter sets, however, the simulations fail on the
Mac (see error message below). The
2008 Jan 02
3
is Power fail transfer possible with asterisk?
Hi. I have a client who wants some way that his analog phones can
call out even after the power is out and the UPS has died -- some way
that a phone can connect directly to an fxo or some such when power is
gone. Any hardware around which can do this? I have heard of some
ATA's which do this, do any of the channel banks have this capability?
Thanks.
--
Your life is like a penny.
2000 Jan 05
0
stock idea dvdt
2004 Nov 25
3
How to make/recieve call using asterisk when there is a power failure?
Hi,
I am supportive of the asterisk, but I have some concern, though the concern
also applies to traditional pbx as well. Hope someone can shine some light
into it. Thanks.
During a power failure situation, analog pstn lines that connect directly to
the analog phones will most likely still be able to make and receive calls.
However, for the Asterisk implementation, unless you have a
2003 Jul 13
2
Line Override Device
Hello,
I am trying to solve a problem that I can foresee when I deploy Asterisk
into a few SOHO situations soon. In Nebraska and in my area of Western
Pennsylvania we have violent thunderstorms in spring and summer and
sometimes very heavy wet snow in Winter. Both type of event will take out
the power of a period of 30sec to 36-hours. So no UPS system would be able
to handle a system for over
2004 Sep 06
1
A naive lsoda question....
Hello,
I am an R newbie, trying to use lsoda to solve standard
Lotka-Volterra competition equations. My question is: how do I
pass a parameter that varies with time, like say, phix <- 0.7 +
runif(tmax) in the example below.
# defining function
lotvol <- function(t,n,p){
x <- n[1]; y <- n[2]
rx <- p["rx"]; ry <- p["ry"]
Kx <-
2008 Sep 16
0
lsoda( linking to GMP for big numbers from C code)
Hi R used with C-code experts,
I had a look at the archives and did not find anything on this, so
hopefully I am not doubling up.
I have previously used the following approach where I needed some very
small/large numbers (using Brobdingnag):
surfacewithdiff <- function(t, y, p)
{
const=p["const"]
kay =p["kay"]
psii=p["psii"]
2013 Apr 21
1
lsoda question from deSolve package
Dear List,
Wonder if you have some thoughts on the following question using lsoda in desolve:
I have the following data and function:
require(deSolve)
times <- c(0:24)
tin <- 0.5
D <- 400
V <- 26.3
k <-0.056
k12 <- 0.197118
k21 <- 0.022665
yini <- c(dy1 = 0,dy2 = 0)
events <- data.frame(var = "dy1",time = c(10,15),value = c(200,100),method =
2005 Oct 26
2
changing memory limits to speed up lsoda
Hi All,
I am running R 2.2.0 on Mac OS 10.4.2, dual G5 processors with 8 Gig
RAM.
I am running a simulation with lsoda that requires ~378 s to complete
one set of time intervals. I need to optimize the parameters, and so
need to considerably speed up the simulation.
I have tried to figure out how to change the appropriate memory
allocation and have search R help and Introductory
2008 Nov 21
1
lsoda warning "too much accuracy requested"
Dear list -
Does anyone have any ideas / comments about why I am receiving the following
warning when I run lsoda:
1: lsoda-- at t (=r1), too much accuracy requested in: lsoda(start, times,
model, parms)
2: for precision of machine.. see tolsf (=r2) in: lsoda(start, times,
model, parms)
I have tried changing both rtol and atol but without success. I saw the
thread in the
2004 Jun 10
0
lsoda with arbitrary zero thresholds (with psuedo-solution)
Dear Hank,
Last question first: really, only you can say for sure if 4e-281 and
5e-11 are small enough; it depends on the units you measure your state
variables in. However, this strategy cannot get the state variables to
exactly 0. Obviously, you could get closer to 0.0 faster by setting the
derivatives even larger in absolute value. You may run into problems
with the solver when the
2009 May 26
2
using lsoda() and nls() together
Thanks to Dieter Menne and Spencer Graves I started to get my way through
lsoda()
Now I need to use it in with nls() to assess parameters
I have a go with a basic example
dy/dt = K1*conc
I try to assess the value of K1 from a simulated data set with a K1 close to
2.
Here is (I think) the best code that I've done so far even though it crashes
when I call nls()
2004 Jun 10
2
odesolve: lsoda vs rk4
I'm trying to use odesolve for integrating various series of coupled 1st
order differential equations (derived from a system of enzymatic
catalysis and copied below, apologies for the excessively long set of
parameters).
The thing that confuses me is that, whilst I can run the function rk4:
out <- rk4(y=y,times=times,func=func, parms=parms)
and the results look not unreasonable:
2003 Nov 05
3
using LSODA in R
R help list subscribers,
I am a new user of R. I am attempting to use R to explore a set of
equations specifying the dynamics of a three trophic level food chain. I
have put together this code for the function that is to be evaluted by
LSODA. My equations Rprime, Cprime, and Pprime are meant to describe the
actual equation of the derivative. When I run LSODA, I do not get the
output that
2008 Apr 09
3
LSODA not accurate when RK4 is; what's going on?
I'm solving the differential equation dy/dx = xy-1 with y(0) = sqrt(pi/2).
This can be used in computing the tail of the normal distribution.
(The actual solution is y(x) = exp(x^2/2) * Integral_x_inf {exp(-t^2/2) dt}
= Integral_0_inf {exp (-xt - t^2/2) dt}. For large x, y ~ 1/x, starting
around x~2.)
I'm testing both lsoda and rk4 from the package odesolve.
rk4 is accurate using step