schoolmath
In connection with the Le Monde puzzle of last week, I was looking for an R function that would give me the prime factor decomposition of any integer. Such a function exists within the package schoolmath, developped by Joerg Schlarmann and Josef Wienand. It is called prime.factor and it returns the prime factors of any integer:
> prime.factor(2016)
[1] 2 2 2 2 2 3 3 7
> prime.factor(2032)
[1] 2 2 2 2 127
> prime.factor(2031)
[1] 3 677
> prime.factor(2039)
2039 is a prime!
[1] 2039
Warning [06/14/10]! As pointed out in this blog by Neil Gunther, schoolmath contains mistakes in the function primes, listing 1 as a prime number but also including decomposable numbers like 133.
Xi'an's Og 
February 18, 2011 at 12:09 am
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June 14, 2010 at 7:37 am
[…] Neil Gunther has pointed out on his blog that the prime number decomposition R package schoolmath contains mistakes in the function primes, listing 1 as a prime number but also including […]
March 31, 2010 at 3:20 pm
If it had not existed, one could also have downloaded free computer algebra systems, such as Xcas.
http://en.wikipedia.org/wiki/Xcas
March 7, 2010 at 1:09 pm
thanks for pointing this out. what else can schoolmath do?
March 7, 2010 at 5:47 pm
The name “says it all”! You can go all kinds of arithmetic high school stuff with the package…