Hi All... A few questions concerning the use of DLLs in R. Before you get scared off and don’t read any further (I’ve seen a lot of talk within the help pages concerning loading DLLs in R) realize that communication between R and my DLLs is solid. The problem arises when comparing the computational performance between calling a *.dll file, compiled using g77 under MinGW version 2.0.0 with package upgrades, and calling an *.exe file, compiled with Compaq Visual FORTRAN Professional Edition 6.6.A. Both calls (.Fortran and system) are made from the R - Tcl/Tk GUI environment. After comparing identical code, compiled as a DLL and EXE, I’ve come to the disappointing realization that the DLL calls take about five times the computational time of the EXE calls. I tried the experiment using a number of different FORTRAN codes with the same results. My first thought was that I was compiling the code incorrectly. The following command is what I typically use to generate the DLL. g77 –shared –o temp.dll temp.f After a short search over the net, I discovered a number of g77 optimization options (e.g. –O, –O2) for compiling. These options had little to no impact on the computational times. Next, I went back to “Writing R Extensions” and started working with the Rcmd SHLIB. This again had little to no impact on computational time. Any ideas, I’m a novice at working with DLLs and know there must be something I’m missing. One option is to just call the EXE, however, it just seems crummy to generate an input file in R, run the EXE which produces an output file, read the EXE output file in R, and finally delete the input and output files. Thanks in advance for any insightful knowledge you bring my way. Regards, Jason R 1.6.2 *************************************** Jason C. Fisher UCLA Graduate Student Civil & Environmental Engineering Dept. 5731 Boelter Hall Box 951593 Los Angeles, CA 90095-1593 Phone Number: (310) 825-2292 Email: stormplot at hotmail.com