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Symbolic Integration, Continued - Printable Version

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Symbolic Integration, Continued - Austin W. - 04-19-2011

Hi all!

A while back, I was lurking on these forums and I came across this thread:
Symbolic Integration

I attempted to integrate dx /(1+x^16) like Mr. von Cube did with his NSpire. However, I used my 50g.

I am almost POSITIVE that I got an answer (Lots of ln and atan terms.)
However, I tried again recently, and I got an INTVX (or RISCH) error:
Unable to factor.

This really isn't terribly important; it just bothers me!
Any ideas as to why it may have worked back then but doesn't now?

Thanks,
Austin W.


Re: Symbolic Integration, Continued - Valentin Albillo - 04-20-2011

Quote:
Hi all!

A while back, I was lurking on these forums and I came across this thread:
Symbolic Integration

I attempted to integrate dx /(1+x^16) like Mr. von Cube did with his NSpire. However, I used my 50g.

I am almost POSITIVE that I got an answer (Lots of ln and atan terms.)
However, I tried again recently, and I got an INTVX (or RISCH) error:
Unable to factor.

This really isn't terribly important; it just bothers me!
Any ideas as to why it may have worked back then but doesn't now?



Most likely one of the following:

1) Insufficient memory. Free a respectable quantity, then try again.

2) Hitting some limit on the number of factors or length of the answer. See parameter settings.

3) Hitting some limit in the depth of factoring. See parameter settings.

If the above doesn't help, try changing the exponent 16 to 2, then 4, then 8, then 16, and see where it fails.

Regards from V.
.


Hey, email me! - Gene Wright - 04-20-2011

Give me a shout, Valentin!


Re: Symbolic Integration, Continued - Marcelo Vanti (Brasil) - 04-20-2011

Hi,

Quote:
2) Hitting some limit on the number of factors or length of the answer. See parameter settings.

3) Hitting some limit in the depth of factoring. See parameter settings.


Please, which parameter settings?
Thanks, Marcelo.


Re: Symbolic Integration, Continued - Marcelo Vanti (Brasil) - 04-20-2011

Hi again,

It worked until n = 6. For greatest values, I got the same error.

Marcelo


Re: Symbolic Integration, Continued - Austin W. - 04-20-2011

Hi there,

I did as you suggested, and I may have partially solved the problem.
In exact mode,I set the "factorize" flag to numeric (I'm afraid I don't have the calculator with me at the moment, and so I can't tell you the flag number) and I use INTVX I'm are asked to switch modes (exact->appx) and I'm are given a large answer with ln and atan terms and a bunch of decimals. Using XQ I can get an integer answer. A wierd thing though, if I try it already in appx mode, the calculator "hangs." No error, it just sits for awhile. It may be that I am too impatient to let it finish. I may be mixing some things up too; I'll go look at it and come back later.

For now though, try setting "Num. factorize" and trying it.

Thanks, all of you for your responses!

-Austin W.


Re: Symbolic Integration, Continued - Austin W. - 04-20-2011

Haha, I changed from second to first person and really messed up my English.
Sorry about that.

-Austin W.