Update README.md

added comment about cosmorec PIC flag

README.md

@@ -60,9 +60,15 @@ wget https://www.cita.utoronto.ca/~jchluba/Recombination/_Downloads_/CosmoRec.v2
 tar -xvf CosmoRec.v2.0.3b.tar.gz
 ```
 
-3. In this path, invoke `make all` to compile CosmoRec.
+3. In the cosmorec `Makefile.in` file, add the `-fPIC` flag to the `CXXFLAGS` parameter, so that line 11 now reads:
 
-4. Now, in the location where you installed camb (this will either be a directory where you have a separate instance of camb, or a directory within your cobaya packages path), locate the `fortran/Makefile_main` file. Add the following two lines all the way at the top:
+```
+CXXFLAGS = -Wall -pedantic -O2 -fPIC
+```
+
+4. You can now invoke `make all` to compile cosmorec.
+
+5. Now, in the location where you installed camb (this will either be a directory where you have a separate instance of camb, or a directory within your cobaya packages path), locate the `fortran/Makefile_main` file. Add the following two lines all the way at the top:
 
 ```
 RECOMBINATION_FILES = recfast cosmorec
@@ -71,7 +77,7 @@ COSMOREC_PATH = <path/to/cosmorec>
 
 Where `<path/to/cosmorec>` is the path where you unpacked CosmoRec in step 2.
 
-5. Recompile the camb fortran library by invoking
+6. Recompile the camb fortran library by invoking
 
 ```
 python setup.py make