LSODE is included iin IDL since 5.1. However the function call and the help entry are not very helpful, i.e. it is not explainend which algortihm is used, stiffness is only mentioned in the cited literature .... In addition not all the options the original LSODE has, including the useful ones, like single-stepping through the integration. I would like to use this integrator,, it seems to be fast but I still have a few questions: * does someone have experience (good or bad) with this function ? * where do I get info about error messsges like % LSODE: lsodar- at current t (=r1), mxstep (=i1) steps % LSODE: taken on this call before reaching tout 500 7.893178e-008 * is there any other routine (in IDL) available for the sollution of large set of stiff ODEs ? * on my computers ( Linux 1GB and Win2K 512MB) the max size is 8000 element, is that a function of the computer used or a general restriction of the code within IDL ? Thenks Theo Brauers