Dear all, I have been trying to use R's optimization routines from C and I have some questions. Specifically, I am testing the usage of nmmin which performs Nelder-Mead optimization in order to learn how to do the above exercise. I understand from the notes in Chapter 5 that the declaration for both optimfn as well as nmmin are included in the header file R_ext/Applic.h so I have included that. Is there anything else (definitions, etc) that needs to be provided in the preprocessor directive? While linking, it appears that nmmin is in libR.so, so I guess I should include that library when I compile the program, is that right? I also wanted to use some of the functions in the Rmath library in the same program. However, when I use it, I get an error in the header files. which says essentially that there are some redeclarations in the header (specifically, Rboolean, TRUE and FALSE). I have defined #define MATHLIB_STANDALONE 1 is there anyother preprocessor directive I should give and define other things needed? Btw, I am using FC-4 and RHEl-4 and I do have the latest versions of R Version 2.2.1 (2005-12-20 r36812). I am happy to provide my test programs that I am using to test my usage of the above optimization routines. Many thanks for any help you can provide! Globe