08/21/2009, 12:38 PM

You may also use the powerseries package that was an outcome/branch of some effort of Andrew and me to put together sage routines for hyperoperations.

I recently adapted the code to work with sage 4.1.1:

http://github.com/bo198214/hyperops/raw/...rseries.py

You would use it for the purpose of iterating exp(x)-1 like:

(This is on a Athlon XP 2500, it consumes roughly 200-300 MB memory.)

"it(w)" does just what one would expect: it iterates the given powerseries by w.

I recently adapted the code to work with sage 4.1.1:

http://github.com/bo198214/hyperops/raw/...rseries.py

You would use it for the purpose of iterating exp(x)-1 like:

Code:

`----------------------------------------------------------------------`

| Sage Version 4.1.1, Release Date: 2009-08-14 |

| Type notebook() for the GUI, and license() for information. |

----------------------------------------------------------------------

In [2]: load formal_powerseries.py

In [3]: P = FormalPowerSeriesRing(QQ)

In [4]: w = PolynomialRing(QQ,'w')([0,1])

In [5]: time sum(P.Dec_exp.it(w)[0:100]);

CPU times: user 326.53 s, sys: 1.49 s, total: 328.02 s

Wall time: 345.83 s

In [7]: P.Dec_exp.it(w)

Out[7]: [0, 1, 1/2*w, 1/4*w^2 - 1/12*w, 1/8*w^3 - 5/48*w^2 + 1/48*w, ...]

"it(w)" does just what one would expect: it iterates the given powerseries by w.