"Is prime?" primitive

[TiTou]

Many languages have that, why not LabVIEW?

See here for implementation details.

This would help me out loads to solve Project Euler's problem faster, at this moment LabVIEW is ranked 53, it would be nice if we had tools that help us improve that.

[altenbach]

Agreed. Mathscript already supports the "isprime" function (also e.g. "primes" and "factors"), so this probably already exists under the hood somewhere. 😉

In plain LabVIEW, we do have "prime factor" though, you could just look at the array size of the output ;))

(your links all point to the euler home page. Do we need to be signed in to get to the right place?) 

[PaulG.]

I logic yes/no output primitive would be ideal, but like altenbach said you can use prime factor and look for an array size output = 1. I made my own years ago while spending time in Project Euler. 

[JÞB]

Another one I've rolled my own on before.

I had way too much time on my hands that day but the vi has been useful over many years

[SteenSchmidt]

I'm about to release a new GPower toolset (it's basically a very efficient string expression parser/evaluator, working title is GPMath) in which I've opted to not include an ISPRIME function, simple due to the fact that such a function simply isn't that useful for small integers as available in LabVIEW.

I'm used to working with HP calculators and have earlier programmed a big_math library in C for the HP50G with an ARM9 CPU, and on that platform it makes sense. On that it's possible to calculate with integers with 200,000 digits for instance, while in LabVIEW we're dealing with max 20 digits. But maybe I should include it in GPMath as well, if there is a use for it?

The above isn't meant to stop an ISPRIME primitive from being included in native LV of course, my toolset would just be able to evaluate "ISPRIME(x) && ISPRIME(y)" for instance... And the mentioned built in Prime Factor VI is only available from LV 2011 onwards, and then only in LV Full and Professional, not in Base.

Cheers,

Steen

[Charles_CLA]

@altenbach, I'd never seen the "prime factor" vi before. However, it appears to have a flaw: if you input "1" into, then it returns "1". Should it not return an empty array as "1" is not a prime number?

[SteenSchmidt]

Even though 1 is not a prime number, prime factorization of 1 is 1 by mathematical definition.

/Steen

[WG-]

Useless idea. It is fairly easy to validate up to a certain degree if a number is prime or not. Certainly up to the largest labview datatype 64 bit numerical value. This has only use if LabVIEW would have a bignum toolkit. Which provides arithmetic operations for arbitrarly large numbers.

[SteenSchmidt]

Just as I wrote... 😉

[Darren]

Check Prime VI is available in LabVIEW 2015 and later