if (have.fsl()){
system.time({
x = array(rnorm(1e6), dim = c(100, 100, 100))
img = nifti(x, dim= c(100, 100, 100), 
datatype = convert.datatype()$FLOAT32, cal.min = min(x), 
cal.max = max(x), pixdim = rep(1, 4))
entropy = fslstats(img, opts='-E')
})
}  
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