# On large numbers

**URL:** <https://boards.straightdope.com/t/on-large-numbers/141721>\
**Category:** Miscellaneous and Personal Stuff I Must Share\
**Created:** [December 10, 2002, 5:57am UTC](https://boards.straightdope.com/t/on-large-numbers/141721 "2002-12-10T05:57:56Z")\
**Posts on this page:** 3\
**Page:** 4

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**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\
**Post date:** [December 17, 2002, 7:18pm UTC](https://boards.straightdope.com/t/on-large-numbers/141721/61 "2002-12-17T19:18:08Z")

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Here we go. [Primitive recursive functions](http://mathworld.wolfram.com/PrimitiveRecursiveFunction.html) at MathWorld. That’s the reputable site I had in mind.

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**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\
**Post date:** [December 17, 2002, 8:14pm UTC](https://boards.straightdope.com/t/on-large-numbers/141721/62 "2002-12-17T20:14:05Z")

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Okay, got that part straight. Note that the MathWorld blurb is “Fortran” oriented. Many programming languages (such as C) allow changeing the for loop parameters during the loop. That violates the condition nec. for primitive recursive.

I was thinking about a classic result by Meyer and Ritchie and their “loop” language. I can’t find out on the Net what their restriction was on loops (and my old class notes are not “easily accesible” to say the least). So for the time being, what loop restriction gives sub-primitive recursive remains a mystery to me. (I’m kinda burned out on Net searching for now. Do you know how hard it is to find “Grzegorczyk” when you don’t remember the spelling?)

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**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\
**Post date:** [February 5, 2003, 5:56pm UTC](https://boards.straightdope.com/t/on-large-numbers/141721/63 "2003-02-05T17:56:26Z")

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And I’m now addicted to MathWorld. 🙂

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