stopPrime {Rfractran}

Function to Stop fracDo When Finding Primes

Description

This function is designed to be fed to fracDo as the argument stopFun. It will send a note to the console every time a prime number is found. It also serves as a sample of what a "stopping function" could look like - notice that despite the name, this function doesn't force-stop fracDo.

Usage

stopPrime(x, mantissa,returnVal = 0)

Arguments

x

The current integer generated with the FRACTRAN generator (fracDo.)

mantissa

Choose the mantissa based on the prime-generating algorithm selected. Must be an added argument to fracDo. See Details.

returnVal

Normally set to zero so as not to terminate the FRACTRAN program. If desired, set to one (or TRUE) to terminate after the first prime is found. Must be an added argument to fracDo. See Details.

Details

There are two well-known prime generators for FRACTRAN, one of which uses powers of two and the other uses powers of 10. Select the mantissa to match one of these, or potentially any other FRACTRAN program which returns values as (mantissa)^(result) . When running fracDo, you must enter the value as an argument after all named arguments. Similarly, if desired, enter a value for returnVal to fracDo.

Value

Returns the specified value of returnVal so that fracDo will or will not terminate. Its "useful" output is cat-ed to the console.

Author(s)

Carl Witthoft <[e-mail]>

Examples

##---The prime generator doesn't terminate, so look for values.
#start with 10,  and result includes a series of values 10^p , p prime 
fracp10 <- fracMake(c(7,99,13,39,36,10,49,7,1,91), c(3,98,49,35,91,143,13,11,2,1)) 
p10 <-fracDo(10,fractions = fracp10, tries = 1000,stopFun=stopPrime, mantissa = 10 )
# primes found are sent to console 
# p10 contains all integers found.