- Reference Read the web page <a href="http://cran.r-project.org/manuals.html" target="_blank">The R Manuals</a>, and the PDF document Writing R Extensions (Chapter 5) in The R Manuals (my mirror <a href="./reference/R-exts.pdf" target="_blank">here</a>). - C code The C code "<a href="./example/Call_R/callR.c" target="_blank">callR.c</a>" will generate 10 random variables from standard normal (mu = 0, sigma = 1) and compute theirs cumulative probability, and sort these 10 random variables, and print all results. ``` #include <R.h> #include <Rmath.h> void callR(){ int i; double mu, sigma, PHI_X, *X; mu = 0; sigma = 1; X = (double *) R_alloc(10, sizeof(double)); Rprintf("Before sort\n"); GetRNGstate(); for(i = 0; i < 10; i++){ X[i] = rnorm(mu, sigma); PHI_X = pnorm(X[i], mu, sigma, 1, 0); Rprintf("X: %f, PHI(X): %f\n", X[i], PHI_X); } PutRNGstate(); R_rsort(X, 10); Rprintf("After sort\n"); for(i = 0; i < 10; i++){ PHI_X = pnorm(X[i], mu, sigma, 1, 0); Rprintf("X: %f, PHI(X): %f\n", X[i], PHI_X); } } ``` - Compile - Linux: ``` SHELL> gcc -shared -o callR.so callR.c -I/usr/lib/R/include/ -L/usr/lib/R/bin/ -lR ``` or ``` SHELL> R CMD SHLIB callR.c ``` The output will be a shared library "<a href="./example/Call_R/callR.so" target="_blank">callR.so</a>" which is a dynamic loading file as the dll file in MS Windows. - R script Create a R script "<a href="./example/Call_R/callR.r" target="_blank">callR.r</a>" to load the library and execute it. ``` dyn.load("callR.so") set.seed(10) out <- .C("callR") dyn.unload("callR.so") ``` - Output The output is as the following, ``` Before sort X: 0.018746, PHI(X): 0.507478 X: -0.184253, PHI(X): 0.426908 X: -1.371331, PHI(X): 0.085136 X: -0.599168, PHI(X): 0.274531 X: 0.294545, PHI(X): 0.615829 X: 0.389794, PHI(X): 0.651656 X: -1.208076, PHI(X): 0.113509 X: -0.363676, PHI(X): 0.358050 X: -1.626673, PHI(X): 0.051903 X: -0.256478, PHI(X): 0.398791 After sort X: -1.626673, PHI(X): 0.051903 X: -1.371331, PHI(X): 0.085136 X: -1.208076, PHI(X): 0.113509 X: -0.599168, PHI(X): 0.274531 X: -0.363676, PHI(X): 0.358050 X: -0.256478, PHI(X): 0.398791 X: -0.184253, PHI(X): 0.426908 X: 0.018746, PHI(X): 0.507478 X: 0.294545, PHI(X): 0.615829 X: 0.389794, PHI(X): 0.651656 ``` - Question Why not to use executable file? How to build a "callR.exe"? See <a href="./standalone.html">Standalone.</a> --- <div w3-include-html="../preamble_tail_date.html"></div>