divisorsRcpp.RdFunction for generating the complete factorization for a vector of numbers.
divisorsRcpp(v, namedList = FALSE, nThreads = NULL)Vector of integers or numeric values. Non-integral values will be coerced to whole numbers.
Logical flag. If TRUE and the length(v) > 1, a named list is returned. The default is FALSE.
Specific number of threads to be used. The default is NULL.
Efficient algorithm that builds on primeFactorize to generate the complete factorization of many numbers.
Returns an unnamed vector if length(v) == 1 regardless of the value of namedList. If \(v < 2^{31}\), the class of the returned vector will be integer, otherwise the class will be numeric.
If length(v) > 1, a named/unnamed list of vectors will be returned. If max(bound1, bound2) \(< 2^{31}\), the class of each vector will be integer, otherwise the class will be numeric.
The maximum value for each element in \(v\) is \(2^{53} - 1\).
## Get the complete factorization of a single number
divisorsRcpp(10^8)
#> [1] 1 2 4 5 8 10 16
#> [8] 20 25 32 40 50 64 80
#> [15] 100 125 128 160 200 250 256
#> [22] 320 400 500 625 640 800 1000
#> [29] 1250 1280 1600 2000 2500 3125 3200
#> [36] 4000 5000 6250 6400 8000 10000 12500
#> [43] 15625 16000 20000 25000 31250 32000 40000
#> [50] 50000 62500 78125 80000 100000 125000 156250
#> [57] 160000 200000 250000 312500 390625 400000 500000
#> [64] 625000 781250 800000 1000000 1250000 1562500 2000000
#> [71] 2500000 3125000 4000000 5000000 6250000 10000000 12500000
#> [78] 20000000 25000000 50000000 100000000
## Or get the complete factorization of many numbers
set.seed(29)
myVec <- sample(-1000000:1000000, 1000)
system.time(myFacs <- divisorsRcpp(myVec))
#> user system elapsed
#> 0.000 0.000 0.001
## Return named list
myFacsWithNames <- divisorsRcpp(myVec, namedList = TRUE)
## Using nThreads
system.time(divisorsRcpp(myVec, nThreads = 2))
#> user system elapsed
#> 0.001 0.000 0.001