R version 4.1.1 Patched (2021-10-12 r81047) -- "Kick Things"
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Platform: x86_64-pc-linux-gnu (64-bit)

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> ## reproducible examples.
> 
> library(parallel)
> 
> if(require(boot)) {
+     run1 <- function(...) {
+         library(boot)
+         cd4.rg <- function(data, mle) MASS::mvrnorm(nrow(data), mle$m, mle$v)
+         cd4.mle <- list(m = colMeans(cd4), v = var(cd4))
+         boot(cd4, corr, R = 500, sim = "parametric",
+              ran.gen = cd4.rg, mle = cd4.mle)
+     }
+     cl <- makeCluster(mc <- 2)
+     clusterSetRNGStream(cl, 123)
+     cd4.boot <- do.call(c, parLapply(cl, seq_len(mc), run1))
+     print(boot.ci(cd4.boot,  type = c("norm", "basic", "perc"),
+                   conf = 0.9, h = atanh, hinv = tanh))
+     stopCluster(cl)
+ }
Loading required package: boot
BOOTSTRAP CONFIDENCE INTERVAL CALCULATIONS
Based on 1000 bootstrap replicates

CALL : 
boot.ci(boot.out = cd4.boot, conf = 0.9, type = c("norm", "basic", 
    "perc"), h = atanh, hinv = tanh)

Intervals : 
Level      Normal              Basic              Percentile     
90%   ( 0.4705,  0.8589 )   ( 0.4620,  0.8597 )   ( 0.4900,  0.8689 )  
Calculations on Transformed Scale;  Intervals on Original Scale
> 
> 
> proc.time()
   user  system elapsed 
  0.206   0.046   0.559