[R-sig-dyn-mod] Difference between ode.2D and lsodes

[Thomas Petzoldt]

Hi,

1) please note that lower case letters are required for the method 
argument, i.e. method="lsodes".


2) then the Details section of the help page ?ode.2D tells us:

"This is the method of choice for 2-dimensional models, that are only 
subjected to transport between adjacent layers.

Based on the dimension of the problem, and if lsodes is used as the 
integrator, the method first calculates the sparsity pattern of the 
Jacobian, under the assumption that transport is only occurring between 
adjacent layers. Then lsodes is called to solve the problem."


In short: ode.2D calculates the sparsity pattern for the special case of 
typical 2D problems and then calls lsodes.


More can be seen from the R source code of ode.2D:

[...]

bandwidth <- 1
out <- lsodes(y = y, times = times, func = func, parms,
    sparsetype = "2D", nnz = c(nspec, rev(dimens), rev(Bnd),
    bandwidth), ...)

[...]


Hope it helps,

Thomas


On 30.09.2017 08:23, amiller at math.utah.edu wrote:
> Hello,
> I have been solving a system of PDEs using method of lines and because my
> system is stiff, I have been using LSODES for the ode solver. However,
> today I tried ode.2D choosing method="LSODES" and found that it is able to
> handle larger systems of ODEs than if I just used LSODES. I was wondering
> what the difference is between the two solvers?
> Thank you,
> Anna