code and tests for BLAS setup in macOS

testsvd.R

# reference for managing BLAS usage -- https://cran.r-project.org/bin/macosx/RMacOSX-FAQ.html#Which-BLAS-is-used-and-how-can-it-be-changed_003f-1

# script

print(extSoftVersion()["BLAS"])
# global matrix value
set.seed(1234)
x = rnorm(500)
y = x %*% t(x)
# compute svd
dosvd = function() svd(y)
# quiet iteration
sink("/tmp/dmp")
tim = system.time(uu <- replicate(100, dosvd()))
sink(NULL)
# timing
tim

# result of source('testsvd.R') with R 4.5.1 as shipped for macOS on old M1 mac
#
#                                                                               BLAS 
#"/Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/lib/libRblas.0.dylib" 
#...
#> tim
#   user  system elapsed 
# 37.253   0.144  37.534 
# 
# # result after switching to vecLib as suggested in FAQ noted above via symlinks
# 
#                                                                                                            BLAS 
#"/System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib" 
#...
#> tim
#   user  system elapsed 
#  4.766   1.670   4.349 
  
# result within container obtained via docker pull bioconductor/bioconductor_docker:devel on jul 19 2025
#
#                                                      BLAS 
#"/usr/lib/aarch64-linux-gnu/openblas-pthread/libblas.so.3" 
#> tim
#   user  system elapsed 
# 88.020  64.182  25.628