sinh/cosh miscalculation?

sinh/cosh miscalculation? - Messages

#1 Posted: 4/21/2010 1:41:20 PM
cos_phi

cos_phi

0 likes in 39 posts.

Group: User

Hello (again)

I posted before but it didn't show up. I won't insist.
However, I may have found a bug, if it's not, please disregard this. I uploaded the file to:

" http://www.easy-share.com/1909986260/Inv.%20Chebyshev.sm " [edit]the link didn't show up properly[/edit]

I'm trying to recreate the files from wxMaxima and I have the denominator as:
wxMaxima: D(k):=1/(sin(x(k))^2*sinh(y)^2+cos(x(k))^2*cosh(y)^2)
SMath: D(k):=1/{sin(x(k))^2*sinh(y)^2+cos(x(k))^2*cosh(y)^2}

wxMaxima: D(1)=.113545
SMath: D(1)=0.0662

I tried with symbolical evaluation:

wxMaxima: 1/(sinh(asinh(3*sqrt(1111))/3)^2/4+(3*cosh(asinh(3*sqrt(1111))/3)^2)/4)
SMath: 16/{4*sinh(asinh(sqrt(9999))/3)^2+12*cosh(asinh(sqrt(9999))/3)^2}

which are one and the same. Is this a bug or am I doing something wrong?


Regards,
Vlad.

PS: I'm using Ubuntu Karmic x64.


[EDIT2]
sinh seems to be the problem:
Maxima: sinh(y)=2.83849
SMath: sinh(y)=5.7625

y=(1/3)*asinh(sqrt(10^(40/10)-1)) and is the same in both programs: 1.7661
[/EDIT2]


[EDIT3, and last]
On http://smath.info/live/?lang=eng x=17661/10000 and sh(x)=2.8385
[/EDIT3]
#2 Posted: 4/21/2010 2:18:03 PM
Andrey Ivashov

Andrey Ivashov

2269 likes in 3729 posts.

Group: Super Administrator

Hello.

Thank you for figuring it out! This is a bug of sinh(..) function. I will fix it of cause, but for now I can suggest a solution: you need to override sinh(x) function on top of the page. Here is the screen:



Sorry for this error
Best regards.
#3 Posted: 4/21/2010 2:19:37 PM
cos_phi

cos_phi

0 likes in 39 posts.

Group: User

I said I won't edit anymore, so I'm replying...

Using (e^y +/- e^-y)/2 gives the true result. Just thought I'd let you know.


[EDIT]
We seem to have posted in ~the same time

Good luck and thank you for this wonderful alternative to Mathcad.

Kind regards,
Vlad.
[/EDIT]
#4 Posted: 6/21/2010 8:52:48 PM
Andrey Ivashov

Andrey Ivashov

2269 likes in 3729 posts.

Group: Super Administrator

Sinh(..) function calculation fixed. Fix will be available with a new version of SMath Studio. For now, you can test calculation using SMath Studio Live.
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