These are settings for the differential equation solver (lsoda) that can be accessed via the R interface. The code listing below is taken directly from the lsoda source code.

## Details

The following items can be set

• hmax (HMAX below); decrease hmax when you want to limit how big of a step the solver can take when integrating from one time to the next time. However be aware that smaller hmax will result in longer run times.

• hmin (HMIN below); don't fiddle with this unless you know what you're doing.

• ixpr (IXPR below)

• maxsteps (MXSTEP below); increase this number when the solver has a long interval between two integration times (e.g. when observation records are far apart).

• mxhnil (MXHNIL below); don't usually modify this one

• atol - the absolute solver tolerance; decrease this number (e.g. to 1E-10 or 1E-20 or 1E-50) when the value in a compartment can get extremely small; without this extra (lower) tolerance, the value can get so low that the number can randomly become negative. However be aware that more precision here will result in longer run times.

• rtol - the relative solver tolerances; decrease this number when you want a more precise solution. However be aware that more precision here will result in longer run times.

aboutsolver, update