README.md: for macOS, recommend sysctl -n hw.ncpu instead of sysctl -n hw.physicalcpu

The number of logical cores may be greater than the number of physical cores,
for example on Intel CPUs with hyperthreading. Using all logical cores makes
more sense in this context.

README.md

@@ -458,10 +458,10 @@ cd $HOME/dynare/slicot
 wget https://deb.debian.org/debian/pool/main/s/slicot/slicot_5.0+20101122.orig.tar.gz
 tar xf slicot_5.0+20101122.orig.tar.gz
 cd slicot-5.0+20101122
-make -j$(sysctl -n hw.physicalcpu) FORTRAN=gfortran OPTS="-O2" LOADER=gfortran lib
+make -j$(sysctl -n hw.ncpu) FORTRAN=gfortran OPTS="-O2" LOADER=gfortran lib
 cp slicot.a /usr/local/lib/libslicot_pic.a
 make clean
-make -j$(sysctl -n hw.physicalcpu) FORTRAN=gfortran OPTS="-O2 -fdefault-integer-8" LOADER=gfortran lib
+make -j$(sysctl -n hw.ncpu) FORTRAN=gfortran OPTS="-O2 -fdefault-integer-8" LOADER=gfortran lib
 cp slicot.a /usr/local/lib/libslicot64_pic.a
 cd $HOME/dynare
 ```
@@ -473,7 +473,7 @@ cd $HOME/dynare/x13as
 wget https://www2.census.gov/software/x-13arima-seats/x13as/unix-linux/program-archives/x13as_asciisrc-v1-1-b59.tar.gz
 tar xf x13as_asciisrc-v1-1-b59.tar.gz
 sed -i '' 's/-static//g' makefile.gf
-make -j$(sysctl -n hw.physicalcpu) -f makefile.gf FC=gfortran LINKER=gfortran FFLAGS="-O2 -std=legacy" PROGRAM=x13as
+make -j$(sysctl -n hw.ncpu) -f makefile.gf FC=gfortran LINKER=gfortran FFLAGS="-O2 -std=legacy" PROGRAM=x13as
 cp x13as /usr/local/bin/x13as
 cd ;
 x13as
@@ -502,7 +502,7 @@ where you need to adapt the path to MATLAB. If you don’t have MATLAB, simply r
 
 - Compile:
 ```sh
-arch -x86_64 make -j$(sysctl -n hw.physicalcpu)
+arch -x86_64 make -j$(sysctl -n hw.ncpu)
 ```
 
 ### Optional: pass the full PATH to MATLAB to run system commands