Merge pull request #808 from katrinabrock/fix-cmdstan-1293

Clarify meaning of "set flag" in cmdstan-guide
stan-dev · Aug 21, 2024 · 9a6b9fb · 9a6b9fb
2 parents 5ae71eb + c120bdb
commit 9a6b9fb
Showing 1 changed file with 7 additions and 5 deletions.
diff --git a/src/cmdstan-guide/parallelization.qmd b/src/cmdstan-guide/parallelization.qmd
@@ -21,7 +21,9 @@ on how to rewrite Stan models to use these functions see [Stan's User guide chap
 Once a model is rewritten to use the above-mentioned functions, the model
 must be compiled with the `STAN_THREADS` makefile flag. The flag can be
 supplied in the `make` call but we recommend writing the flag to the
-`make/local` file.
+`make/local` file. If the `STAN_THREADS` flag is defined/non-empty,
+threads will be enabled.
+
 
 An example of the contents of `make/local` to enable threading with TBB:
 
@@ -77,7 +79,7 @@ implementations are [MPICH](https://www.mpich.org/) and [OpenMPI](https://www.op
 Once a model is rewritten to use `map_rect`, additional makefile flags
 must be written to the `make/local`. These are:
 
-- `STAN_MPI`: Enables the use of MPI with Stan if `true`.
+- `STAN_MPI`: Enables the use of MPI with Stan if defined.
 - `CXX`: The name of the MPI C++ compiler wrapper. Typically `mpicxx`.
 - `TBB_CXX_TYPE`: The C++ compiler the MPI wrapper wraps. Typically `gcc` on Linux and `clang` on macOS.
 
@@ -158,8 +160,8 @@ Follow Intel's install instructions given [here](https://software.intel.com/cont
 ### Compiling
 
 In order to enable the OpenCL backend the model
-must be compiled with the `STAN_OPENCL` makefile flag. The flag can be
-supplied in the `make` call but we recommend writing the flag to the
+must be compiled with the `STAN_OPENCL` makefile flag defined/non-empty.
+The flag can be supplied in the `make` call but we recommend writing the flag to the
 `make/local` file.
 
 An example of the contents of `make/local` to enable parallelization
@@ -169,7 +171,7 @@ with OpenCL:
 STAN_OPENCL=true
 ```
 
-If you are using OpenCL with an integrated GPU you also need to add the `INTEGRATED_OPENCL` flag, as the sharing of memory between CPU and GPU is slightly different with integrated graphics:
+If you are using OpenCL with an integrated GPU you also need to define the `INTEGRATED_OPENCL` flag, as the sharing of memory between CPU and GPU is slightly different with integrated graphics:
 
 ```
 INTEGRATED_OPENCL=true