R: typos in core detetection

software/r.rst

@@ -114,8 +114,7 @@ Example :samp:`srun -c 16 --pty /bin/bash`
     library(parallel)
     library(gmp)
 
-    cores <- Sys.getenv("SLURM_ARRAY_TASK_ID")
-    cores <- if (cores == '') 1 else as.numeric(cores)
+    cores <- as.integer(Sys.getenv('SLURM_CPUS_PER_TASK', unset=1))
 
     data <- matrix(as.bigz(2**521)-1, 16)
     mclapply(data, factorize, mc.cores=cores)
@@ -138,8 +137,7 @@ Alternatively you can use `%dopar%` and `foreach`:
     library(doMC)
     library(gmp)
 
-    cores <- Sys.getenv("SLURM_ARRAY_TASK_ID")
-    cores <- if (cores == '') 1 else as.numeric(cores)
+    cores <- as.integer(Sys.getenv('SLURM_CPUS_PER_TASK', unset=1))
     registerDoMC(cores)
 
     foreach(i=seq(1,16)) %dopar% {