[tinspire] Recursive function

[Jim Fullerenex]

Hi everyone,

I need some help here on recursively-defined functions.

I'm trying to define the Ackermann–Péter function

  http://en.wikipedia.org/wiki/Ackermann_function#Table_of_values

According to the table of values, apf(3,4) should be 125. First of all, the result 125 is way below Nspire's numerical capability (it can handle up to 10^1000 !). Second, the recursion of apf(3,4) is not that much to blow up! But my CAS gives "Error: Resource exhaustion"

Also, when defining "hyperoperation"  http://en.wikipedia.org/wiki/Hyperoperation I get the same problem: resource exhaustion when there's actually so little to be done.

Can anyone help me out, or give me an explanation? Thanks!

Best,

Jim

[John Hanna]

 

My version below works OK. Perhaps your piecewise notation is getting in the way?

An interesting challenge for CS students is to display the evaluation process!

 

 

 

     John Hanna

     jeh...@optonline.net

     www.johnhanna.us

     T³ - Teachers Teaching with Technology

     "A cowchip is paradise to a fly."

 

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[Jim Fullerenex]

Thanks John. But I guess you're trying the recursion on the computer software, right?

I just tried. The function still blows up on hh, even if it's not defined in a piecewise manner. But the SS works fine.

It seems that ak(3,4) has 127 levels of recursion. So maybe Nspire is still not good at handling that much. ;)

Best,

Jim

2011/12/24 John Hanna <johne...@gmail.com>