`RxODE` installation under R for Windows
========================================

These notes briefly describe steps to properly install `RxODE` and to
ensure `Rtools` (https://cran.r-project.org/bin/windows/Rtools/) are properly 
configured to avoid compilation issues during the use of `RxODE`. 

In a nutshell, installing `RxODE` is very straight forwad, but installing
and configuring `Rtools` is a bit more delicate and you need to 
carefully follow the instructions in the "R Installation and Adminstration" 
manual, in particular Section 6.3, and Appendix D "The Windows Toolset". 
We point out a couple of details worth extra attention.  Please read on.

Steps:
------

1. Install the appropriate `Rtools` for your R for Windows version,
   e.g., `Rtools` 3.2 for R versions 3.1.x through 3.2.x (for full details
   see http://cran.r-project.org/bin/windows/Rtools/). A couple of 
   important details:

   * When installing `Rtools`, in the "Select Components" dialog box, 
     you may select the default "Package authoring installation".

   * In the "Select Additional Tasks" dialog window, check the
     option "Edit the system PATH".  This is important to be able to
     locate the C, Fortran compilers and other tools needed during 
     the use of `RxODE`.

   * A simple way to test whether `Rtools` was properly installed is
     to compile the `hello.c` program.  Simply open a new MSDOS command 
     window, create a text file `hello.c` and compile it as follows:
   
     ```
     C:\hello> type hello.c
     #include<stdio.h>
     
     void main(int argc, char **argv)
     {
         printf("Hello World!\n");
     }

     C:\hello> gcc -o hello hello.c

     C:\hello> .\hello
     Hello World!
     ```

     If you get the error `gcc: error: CreateProcess: No such file or
     directory` then you know `Rtools` was not properly installed, in
     particular, it did not update your system `PATH` variable.

2.  Obtain the `RxODE` package, either from github or CRAN.  The 
    installation requires use of the gcc compiler, so you'll know if Step 1 
    was successfully executed.

    * CRAN. Use the usual method for installing pacakges from CRAN.

    * GitHub. First install the `devtools` package (if needed) and 
      then `RxODE` from GitHub.  You may want to avoid using a library 
      folder that has spaces in its name (see question 4.1 in the 
      "R for Windows FAQ" and the pointers therein).  As of `RxODE`
      version 0.5-1, we've been able to test installations on folder with 
      spaces in their name, but you may want to be on the safe side.
      
      ``` 
      install.packages("devtools")
      library("devtools", lib = "C:/Rlib")
      install_github("nlmixrdevelopment/RxODE")
      ```

3. Test the `RxODE` installation:

    ``` 
    library("RxODE", lib = "C:/Rlib")
    demo("demo1","RxODE")
    ```

If the demo runs without error, click on the plot window and see if a 
new plot comes up each time. If so, `RxODE` has been installed correctly.

See `browseVignettes("RxODE")` for an extended example on using 
`RxODE` for simulations.

