Rmath | Statistical Distributions from R

I'm trying to draw a random sample from 1,2,3,4 under a given probability vector of length four in C, with the help of Rmath.h. I found this line of code could do this for me.

inline void rmultinom(int n, double* prob, int k, int* rn)

For example, I can write it to draw one random sample.

double p[4]={.1, .2, .3, .2};

rmultinom(1, p, 1, int* rn)

However, I'm lost what this 4th argument should be. In R, the rmultinom function only requires the first three arguments. Another question is what is returned from this function. Is there any convenient way for it to return with one of 1, 2, 3, 4?

currently I am introducing myself to C to extend my R-functions. I wrote a function in C for some computations and they work fine. But as soon as I write a wrapper in R itself there seems to be some mistake. Consider my C-function as "colV" and "abc" as some arbitrary matrix.

The statement (R) .Call("colV", abc, ncol(abc), nrow(abc)) works totally fine (everytime, no matter how often I use it), whereas

I have a problem where I need to numerically integrate a univariate function with multiple extra inputs other than the variable that's being integrated over. The integration is from zero to infinity.

I said without extra parameters because I already defined a class with the extra parameters being the private member variables. And then the operator functor is defined to accept just the integration variable (hence, univariate). With this class, I want to use the GSL numerical integration library (gsl/gsl_integration.h) to do the integration. Is there a way to define a member function for this integration inside the class using GSL?

I have a large dataframe as below:

df1 (sample data)

I want to use the cpp functions of an R-package (AlgDesign - https://github.com/jvbraun/AlgDesign/tree/master/src) within my own cpp project.

My usual IDE is Visual Studio 2015. I have found this related post Building R packages (C API) with Visual Studio (and How do I compile a dll with R and RCPP?) So I installed MinGW and CodeBlocks IDE on my Windows 8.1 and retry. I added the "Rdir/include" path to the "Project build options->search directories->compiler" within CodeBlocks.

But I still get "undefined reference _GetRNGstate" which is equivalent to MSVC "unresolved external symbol _GetRNGstate". So i guess the issue is a missing lib like the original questioner already mentioned. But i could not figure out which one either. There is no .lib file in my R-install dir.

Furthermore is not my intend to use Rcpp or to build an own R-package, I just want to access the SEXP FederovOpt(..args) function within my own cpp-project´

Edit: Lets say i want to transfer the AlgDesign src file function by function into an empty project. At some point I'll reach this:

I am wanting to use the dbeta function in the Rmath package of Julia with the following call:

I experience a crash of R if I call a C function (from R) repeatedly.

I am a newbie in writing C functions and I think that the issue of a R crash I am experiencing is the memory allocation in C. I know that one can free the memory in C, but I cant figure out how exactly and on which parameters. Can anybody help me out here?

I will post a working example here and my issue/question again at the end.

This is the C-Code (credits: the code is based on the code of the mcplr package by Marteen Speeklenbrink (https://github.com/rforge/mcplr).

I want to process two raster images (Ra and Rb), with Ra is the pixel value itself and Rb the values of its neighbors. taking sum as an example, assuming an 3*3 neighbors, for each pixel in Ra I will add its value to values of the neighbor pixels in Rb, an finally i will get another image.

The R raster package provides a focal function, which works only on one image input, i tried to modify the C++ code (enter link description here) to accept two image input using Rcpp. The modified code works well if there is no missing values in the input image of Rb. However, R always aborts if there is NA in Rb. Specifically, abort at the second or third test. it may be similar to this post. however, it did not crash if no NA in the input Rb. It seems i did not handle NA correctly. I do not have deep knowledge on C++, Can somebody help me check this?

here is my cpp file:

UPDATE Previous example is complicated, hence please allow me to use a simpler example as shown below:

Here is the Rcpp code: