R Under development (unstable) (2024-08-17 r87027 ucrt) -- "Unsuffered Consequences"
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> library(expm)
Loading required package: Matrix

Attaching package: 'expm'

The following object is masked from 'package:Matrix':

    expm

> 
> source(system.file("test-tools.R", package= "expm"), keep.source=FALSE)
Loading required package: tools
> ## -> assertError()... doExtras
> doExtras
[1] FALSE
> 
> ## Missing REPROTECT(), till 2014-09-03 [because 'A' is *integer*]:
> set.seed(17)
> n <- 300
> A <- matrix(rbinom(n^2, size=1, prob=0.1), n,n)
> stopifnot(is.integer(A))
> A2 <- A %^% 2
> for(i in 1:100) {
+     A. <- A %^% 2
+     if(!isTRUE(all.equal(A2, A.)))
+         cat("not equal; i=",i,"\n")
+ }
> ## MM: On nb-mm3, I get a different error which shows memory corruption:
> ##     REAL() can only be applied to a 'numeric', not a 'character'
> ## or  REAL() can only be applied to a 'numeric', not a 'NULL'
> 
> ## Check that *large* matrices now work
> if(FALSE) ## << even m %^% 2 takes > 20 hours (!!!) [but no longer stops early!]
+ if(doExtras && require("sfsmisc") &&
+    exists("Sys.memGB", "package:sfsmisc", mode="function") &&
+    sfsmisc::Sys.memGB() > 50) { ## seems to need   3 x size(m)
+     ##
+     n <- 46341
+     print(as.integer(n^2))# integer overflow
+     cat("Creating large matrix 'm' (more than max_int entries):\n ")
+     print(system.time(m <- diag(x = (1:n)^3, nrow = n))) # 9.1 sec
+     i <- 1:(n-1)
+     print(system.time( m[cbind(i,i+1)] <- i ))           # 11.3 sec
+     cat("object.size(m): "); print(object.size(m), units="Gb")
+     ## 16 Gb (= 17.78 e9 bytes)
+     ## This __STILL__ takes hours
+     cat("m %^% 2: "); print(system.time(m2 <- m %^% 2))
+     ##       user     system    elapsed
+     ## 127199.580   9608.373 137236.405  ==>
+ 
+     cat("m %^% 4: "); print(system.time(m4 <- m %^% 4)) #
+ }
> 
> 
> proc.time()
   user  system elapsed 
   4.07    0.39    4.45