# HP50 Integraton - 'Xt' Variable..?? - Hewlett Packard

This is a discussion on HP50 Integraton - 'Xt' Variable..?? - Hewlett Packard ; Hi - When attempting to integrate some harder (but far from impossible) expressions, mode set to Real, variable VX= 'X', I get a delay followed by the integral repeated with every occurrence of 'X' replaced by 'Xt'. What does this ...

# Thread: HP50 Integraton - 'Xt' Variable..??

1. ## HP50 Integraton - 'Xt' Variable..??

Hi -
When attempting to integrate some harder (but far from impossible)
expressions, mode set to Real, variable VX= 'X', I get a delay
followed
by the integral repeated with every occurrence of 'X' replaced by
'Xt'.
What does this mean? Is there some flag setting that will make
the integral come out correctly on the HP ??

Thanks, Richard.

2. ## Re: HP50 Integraton - 'Xt' Variable..??

Sorry, this means that there is no built-in integration pattern
available, so generally, you're out of luck.

(However, sometimes you can try some clever substitutions with SUBST.
For example, consider

'C/X^N' INTVX

which results in C*INT(1/exp(N*LN(Xt),Xt,X).

Now substitute, say 'LN(Xt)=Z', with SUBST,

which results in C*INT(exp(Z)/exp(Z*N),Z,LN(X)). Aha!

Now evaluate this integral with EVAL.

It works! You get -C/((N-1)*exp((N-1)*LN(X)))

And if you don't like the exponential expression in the denominator,
you can fix that with
EXP2POW. )

On Jun 18, 8:30 pm, Richard wrote:
> Hi -
> When attempting to integrate some harder (but far from impossible)
> expressions, mode set to Real, variable VX= 'X', I get a delay
> followed
> by the integral repeated with every occurrence of 'X' replaced by
> 'Xt'.
> What does this mean? Is there some flag setting that will make
> the integral come out correctly on the HP ??
>
> Thanks, Richard.

3. ## Re: HP50 Integraton - 'Xt' Variable..??

I had the same problem. Apparently, it's caused by some cas system
flags not in the correct state.

type cascfg, and press enter. That may solve your problem. It solved
the problem for me.

On Jun 18, 9:30 pm, Richard wrote:
> Hi -
> When attempting to integrate some harder (but far from impossible)
> expressions, mode set to Real, variable VX= 'X', I get a delay
> followed
> by the integral repeated with every occurrence of 'X' replaced by
> 'Xt'.
> What does this mean? Is there some flag setting that will make
> the integral come out correctly on the HP ??
>
> Thanks, Richard.

4. ## Re: HP50 Integraton - 'Xt' Variable..??

Thanks for the suggestion. I ran 'cascfg', with no apparent effect at
all.
Integral still comes out as before. But thanks. Glad it worked for
you.
jrc

On Jun 19, 1:46 pm, odobo wrote:
> I had the same problem. Apparently, it's caused by some cas system
> flags not in the correct state.
>
> type cascfg, and press enter. That may solve your problem. It solved
> the problem for me.
>
> On Jun 18, 9:30 pm, Richard wrote:
>
> > Hi -
> > When attempting to integrate some harder (but far from impossible)
> > expressions, mode set to Real, variable VX= 'X', I get a delay
> > followed
> > by the integral repeated with every occurrence of 'X' replaced by
> > 'Xt'.
> > What does this mean? Is there some flag setting that will make
> > the integral come out correctly on the HP ??

>
> > Thanks, Richard.

5. ## Re: HP50 Integraton - 'Xt' Variable..??

Thanks for suggestion. However, I don't seem to be able to use this
idea,
as I never get a result - just the reprinted integral sign with an
integrand
with 'Xt' instead of 'X' as the variable. If I repeat EVAL, I get same
thing
again with 'Xtt', etc ad nauseum.

Perhaps you mean to make a substitution into the integral itself -
ahh.
I will try that one.

jrc

On Jun 18, 10:51 pm, "hgab...@xmission.com"
wrote:
> Sorry, this means that there is no built-in integration pattern
> available, so generally, you're out of luck.
>
> (However, sometimes you can try some clever substitutions with SUBST.
> For example, consider
>
> 'C/X^N' INTVX
>
> which results in C*INT(1/exp(N*LN(Xt),Xt,X).
>
> Now substitute, say 'LN(Xt)=Z', with SUBST,
>
> which results in C*INT(exp(Z)/exp(Z*N),Z,LN(X)). Aha!
>
> Now evaluate this integral with EVAL.
>
> It works! You get -C/((N-1)*exp((N-1)*LN(X)))
>
> And if you don't like the exponential expression in the denominator,
> you can fix that with
> EXP2POW. )
>
> On Jun 18, 8:30 pm, Richard wrote:
>
> > Hi -
> > When attempting to integrate some harder (but far from impossible)
> > expressions, mode set to Real, variable VX= 'X', I get a delay
> > followed
> > by the integral repeated with every occurrence of 'X' replaced by
> > 'Xt'.
> > What does this mean? Is there some flag setting that will make
> > the integral come out correctly on the HP ??

>
> > Thanks, Richard.

6. ## Re: HP50 Integraton - 'Xt' Variable..??

On Jun 19, 11:23 pm, Richard wrote:
> Thanks for suggestion. However, I don't seem to be able to use this
> idea,
> as I never get a result - just the reprinted integral sign with an
> integrand
> with 'Xt' instead of 'X' as the variable. If I repeat EVAL, I get same
> thing
> again with 'Xtt', etc ad nauseum.
>
> Perhaps you mean to make a substitution into the integral itself -
> ahh.
> I will try that one.
>
> jrc
>
> On Jun 18, 10:51 pm, "hgab...@xmission.com"
> wrote:
>
> > Sorry, this means that there is no built-in integration pattern
> > available, so generally, you're out of luck.

>
> > (However, sometimes you can try some clever substitutions with SUBST.
> > For example, consider

>
> > 'C/X^N' INTVX

>
> > which results in C*INT(1/exp(N*LN(Xt),Xt,X).

>
> > Now substitute, say 'LN(Xt)=Z', with SUBST,

>
> > which results in C*INT(exp(Z)/exp(Z*N),Z,LN(X)). Aha!

>
> > Now evaluate this integral with EVAL.

>
> > It works! You get -C/((N-1)*exp((N-1)*LN(X)))

>
> > And if you don't like the exponential expression in the denominator,
> > you can fix that with
> > EXP2POW. )

>
> > On Jun 18, 8:30 pm, Richard wrote:

>
> > > Hi -
> > > When attempting to integrate some harder (but far from impossible)
> > > expressions, mode set to Real, variable VX= 'X', I get a delay
> > > followed
> > > by the integral repeated with every occurrence of 'X' replaced by
> > > 'Xt'.
> > > What does this mean? Is there some flag setting that will make
> > > the integral come out correctly on the HP ??

>
> > > Thanks, Richard.

The Xt and Xtt etc simply mean that as formulated, the method chosen
on the 50g cannot do the integration.

Another approach has to be taken using substitution perhaps, but
another approach at last.

The HP50g learning modules found here:

http://h20331.www2.hp.com/Hpsub/down...0gPDFfiles.zip
(in one zip file)

or here:

http://h20331.www2.hp.com/hpsub/cach...0-225-121.html
(as individual PDFs)

give several good examples of doing integration, including solving
problems that at first appear intractable. You might also search of
the "Calculus marathons" on hpcalc.org. They are full of wonderful
ideas.

Good luck,
Gene