Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
In article <4fug1n$9br@morrow.stanford.edu>, tom@quake.Stanford.EDU (Thomas Berger) wrote: > A related question: if I end up having to not be lazy and type in a book > algorithm, would it be faster to implement as a CALL_EXTERNAL or a native > IDL routine? I have no experience with external calls; someone told me they > can be slow due to translation (?). Depends on how long the routine is. Short routines that are clear and easy to translate, do it in IDL -- more than a couple of pages, especially if you have the code already on the machine, use CALL_EXTERNAL. My experience is that CALL_EXTERNAL is not too difficult to use, but it is very difficult to debug external routines using IDL. Make sure they work standalone before you try to link them to IDL with CALL_EXTERNAL, then test them with test programs within IDL that are similar to your external test programs. External routines usually need to be compiled and linked differently on different platforms, but the IDL side of things is pretty portable. I don't know any reason why external calls would be slow. (Except for slow external algorithms, of course. :-) ) Regards, Ken Bowman -- Kenneth P. Bowman, Assoc. Prof. 409-862-4060 Department of Meteorology 409-862-4132 fax Texas A&M University bowman@csrp.tamu.edu College Station, TX 77843-3150 On the Internet, everyone will be famous for 15 milliseconds.