It appears that Rich Cooper's definition of "iterate" is to loop with
a counter that advances from one element of a set to the next. It is
unclear what restriction there is on the step that does the advancement.
It probably has to be a fixed value (like a FORTRAN DO statement), but
may not be restricted to the number 1. Rich, do you allow positive
integers other than 1, negative integers, and non-integers as iterative
steps? It evidently does not include taking the next element from a
list. (01)
Rich Cooper's "iterate" does not cover the more advanced C FOR statement
which allows an arbitrary reassignment of the loop counter for each
step of the loop. If this were allowed, the following would be an
iteration of primes.
nextPrime = 2;
for (i = 2, i < upperLimit, i = nextPrime)
[calculate new value of nextPrime]; (02)
If the loop counter for Rich Cooper's iterate has to be a fixed value,
the statement that "there is no function that can iterate the primes
directly" seems to simply mean that there is not a fixed integer
difference between all primes. (03)
Rich, please clarify if this your meaning of the term "iterate", or
if not, what restrictions you place on the assignment of the next
value in the iteration. If it has to be taking the next value from
a list, wouldn't the list of calculated primes be acceptable? That
could have been done in the 1970s with C, although not in the 1950s
with FORTRAN II. E.g.:
sieve[0] = 2;
primeCounter = 0;
for (i = sieve[primeCounter++], i < upperLimit,
i = sieve[primeCounter++])
<calculate next prime and store it into sieve[primeCounter]>; (04)
My definition of "iterate" would consider this to iterate through the
primes. (05)
== doug foxvog (06)
On Thu, October 14, 2010 1:19, Randall R Schulz said:
> On Wednesday October 13 2010, Rich Cooper wrote: (07)
>> The whole point is that there is no function that will iterate the
>> primes directly. The code you wrote will EVENTUALLY iterate primes
>> as a BYPRODUCT of iterating integers and testing them, but that code
>> doesn't produce each prime directly, once per iteration, without
>> iterating other types.
>
> Then there is no iterator that directly iterates anything. It's all
> by-products of something else down to the level of electrons and holes
> cascading through the semiconductor material from which transistors are
> fabricated. And while the electrons are (putatively) primitive,
> semiconductor materials are aggregates and the phenomenon of
> semiconductivity is a bulk property, so there are deeper levels even
> than that.
>
>
>> The method you are using is often called Eratosthenes' Sieve, which
>> is a well known method to calculate primes, but NOT to iterate them.
>> The difference is in what is being enumerated inside the code.
>
> I gotta' say, this sounds like an entirely specious distinction to me.
> But what do I know? I've only been writing computer code for 34 years.
>
>
>> -Rich
>
>
> Randall Schulz
>
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> (08)
=============================================================
doug foxvog doug@xxxxxxxxxx http://ProgressiveAustin.org (09)
"I speak as an American to the leaders of my own nation. The great
initiative in this war is ours. The initiative to stop it must be ours."
- Dr. Martin Luther King Jr.
============================================================= (010)
=============================================================
doug foxvog doug@xxxxxxxxxx http://ProgressiveAustin.org (011)
"I speak as an American to the leaders of my own nation. The great
initiative in this war is ours. The initiative to stop it must be ours."
- Dr. Martin Luther King Jr.
============================================================= (012)
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