Trouble integrating on 49g+



#2

If I try to integrate the expression c/(x^n) the calc is unable to integrate it. If I change the n to a number it has no trouble integrating. I have tried changing the flag 105 for exact mode and that doesn't help. Any ideas on what I can do to make the calc integrate with a variable there instead of a number?


#3

Interesting, I get the same result using c/(x^n) and c*x^-n: both giving c * integral(1/(e^(n*ln x) dx)
where the answer should be

c*-n*x^(-n-1)


#4

Hi Jason, Eddie, folks;

I did not actualy tried what I'm posting here, but I guess it's worth a try.

As I see, 'n' in 'c/(x^n)' is a number, right? The HP49G+ does not know it is a number unless you tell it. If I am not wrong (from the excelent HP48G documentation), the recognizable constants are:

N1, N2, N3...

What about trying 'c/(x^N1)' instead of 'c/(x^n)'? Based on the answer you obtained, Eddie (c*integral(1/(e^(n*ln x)dx), 'n' has been considered as a general variable, that can contain a function.

I may also be copletely out of my mind...

Cheers.

Luiz (Brazil)

Edited: 7 Feb 2005, 7:35 p.m.


#5

I tried your suggestion of using N1 instead of n and that didn't work, but thanks for the suggestion anyway.


#6


#7

nope tried that too


#8

I tried making N a complex number and it returned 'C*INT(1/EXP(0,3))*LN(Xt)),Xt,X)'

Trying IBP (Intergration by parts) gives 'X*N*C*X^N/(X*X^(N*2))'

The RISCH function gives 'C*INT(1/EXP(N*LN(Xt)),Xt,X)'

This may be a disadvantage of look up tables(?).

Just for curiousity, the HP-39 (not G+) returned the same expression.

#9

If I remember well, integral(c/(x^n)) is -c/(n-1)/x^(n-1) ONLY IF n<>1, otherwise integral is c*ln(x) or maybe c*ln(abs(x)).

I'm not expert if HP-49G CAS, but maybe there is a way to add the condition n<>1.

J-F

#10

Alg48, running on my 48GX, gives:-(C/(N-1)*X^(-N+1))


#11

I haven't use alg48 on a 48 before can you think of any specific settings that are set on your calc?


#12

Alg48 only needs "exact" arguments. In this case, f(x) is on level 2, the variable X, on level 1, and then INTGR.


(If you are interested, Erable -mother of the 49 CAS- is unable to integrate this problem)

R Lion


Possibly Related Threads...
Thread Author Replies Views Last Post
  trouble flashing wp34s under Linux Glenn Becker 8 369 07-23-2013, 02:21 AM
Last Post: Marcus von Cube, Germany
  TVM WP34s trouble Jim P 4 286 06-28-2013, 07:31 AM
Last Post: fhub
  Trouble dumping Pioneer ROM via IR Neil Hamilton (Ottawa) 6 302 06-20-2013, 08:14 AM
Last Post: Neil Hamilton (Ottawa)
  41CL :TROUBLE IN FILE TRANsFER aurelio 22 916 06-18-2013, 03:44 PM
Last Post: aurelio
  Trouble entering a HP35s program line Arno 2 206 04-05-2013, 06:28 PM
Last Post: Arno
  wp34s reflashing trouble... Calckidd (USA) 3 180 03-04-2013, 04:32 PM
Last Post: CalcKidd (USA)
  [41CL] Trouble compiling CLWriter.cs Dan Grelinger 3 186 02-17-2013, 10:52 PM
Last Post: Dan Grelinger
  Trouble with RS-232/HP-IL Interface (HP 82164A) Hans Holzach 9 430 01-08-2013, 01:52 AM
Last Post: Marcus von Cube, Germany
  HP28S battery door trouble David Griffith 23 765 02-08-2012, 08:24 AM
Last Post: Neil Hamilton (Ottawa)
  WP 34S: trouble with CLSTK Miguel Toro 4 183 10-22-2011, 07:36 AM
Last Post: Miguel Toro

Forum Jump: