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Terrible Problem With Laplace And V3.03


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#1 acid111

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Posted 24 May 2008 - 04:18 PM

hi

i have tried to solve this, and get the RIGHT solution with Classpad-Manager v3.02:
Posted Image


But, if i try to solve it with my classpad v3.03, i get a WRONG Solution:

Posted Image


What is wrong ? can you help me ?

#2 afshin_electronic

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Posted 24 May 2008 - 05:31 PM

tried it ...
its the same here too ...

are you sure the first answer is RIGHT and the other one is WRONG ...

#3 afshin_electronic

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Posted 24 May 2008 - 05:43 PM

just solved it the old fashioned way ... using pen and paper ...

the first answer (OS 3.02) is RIGHT and the second one (OS 3.03) is WRONG ...

I think someone has to send Casio a feedback on this problem ..... so they may fix it in the next patch ...

this really freaks me out ... because I have to use Laplace Transformations in my upcoming exams ...... and I was counting on CP for that .....

looks like the bugs are never going to end .....

Edited by afshin_electronic, 28 January 2009 - 08:10 PM.


#4 The_AFX_Master

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Posted 24 May 2008 - 05:45 PM

I'm not an expert on laplace transforms.. in fact i saw them years ago and as i don't use them, i almost forgot them..

Did you email casio?.. search on the casio educational site for a "contact us"

#5 acid111

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Posted 24 May 2008 - 06:02 PM

yes, the first is right...
ok, then it is a new bug in v3.03, nice...

no, i did not contact Casio, because my english is not good...
Can someone of you send this bug?

#6 afshin_electronic

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Posted 24 May 2008 - 07:13 PM

I added the above BUG in my CLASSPAD BUG BOOK ... so I wont mistake it in future.....

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

and also I figured out what the problem (BUG) is.

looks like the new OS is allergic to SIN() and COS() in Laplace Transforms when there appears a Parameter as a fraction in the triangular equations ...

lets make it clear with an example:
calculate these in your new OS 3.03:

laplace (sin(t/c),t,S )

the result is: S/(S^2+(1/c^2))

now try:

invlaplace (ans,S,t)

the result would be: (c^2).cos(t/c)

see ... it gives the wrong answer according to what we gave it in the first place ...

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

repeat the same procedure but this time replace sin() with cos() ..... the same BUG will appear


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

its simple ... if in the result of an invlaplace() in OS3.03, you saw a sin() or cos() with fractional parameters in it .... the answer would definitely be WRONG ... and DONT USE IT....

find some other ways to solve the question .......

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

by the way .. AFX_MASTER , would you please report this bug with some screenshots to Casio ......
I dont know how to do that and as you see my English is poor .....


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

and heres another bug in Laplace transform :

you cannot use " T " as a parameter in Laplace transform because is says : "ERROR! INVALID DIMENSION" .. its allergic to this one too !!!!

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#7 acid111

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Posted 24 May 2008 - 08:13 PM

but why did it change from version 3.02 to 3.03 ?
there was no problem with laplace, and they have changed something

#8 ECE

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Posted 26 May 2008 - 01:01 PM

Hi,
I tried all the above, it seems that the problem is in the inverse-Laplace transform, not in the Laplace transform. The results for Laplace cos(t/c) =s/(s^2+(1/c^2)) is correct and for sin(t/c)= 1/c(s^2+(1/c^2)) is also correct. it seems that in the Laplace inverse it is multiplying the results with the constant ? c ?. Note that if you use a number in stead of a constant, you will get a correct answer!!
Example1: invLaplace(s/(s^2+1/25),s,t)
Result: cos(t/5) which is correct
Example2: invLaplace(s/(s^2+1/c^2),s,t)
Result: (c^2).cos(t/c) which is incorrect.
I tried to use ? T ?as a parameter, it worked fine in my os.v 3.03.
The cpm v.3.00 gave all correct results.

#9 acid111

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Posted 15 June 2008 - 11:02 AM

Did anybody send a message to casio ?

#10 hellas1

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Posted 16 June 2008 - 05:10 PM

Hi all,

Since no one sent a message to Casio regarding this issue, I will.
hellas1

Update: 1:40 pm ET (U.S.)
I have sent this issue via e-mail to Casio. I'll post what answer(s) they give.
hellas1

#11 ECE

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Posted 17 June 2008 - 08:51 AM

thank you hellas1.

#12 weirleader

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Posted 12 August 2008 - 05:12 PM

I'm curious if this was ever resolved...

has there been no response in two months???

#13 Guest_hellas1_*

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Posted 12 August 2008 - 10:11 PM

Hi,

This issue "resolution" was posted by me in my "What Casio told me!" Thread.

We need to wait for OS 3.04 to come out to fix a number of bugs.

hellas1

#14 weirleader

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Posted 13 August 2008 - 05:51 PM

Hi,

This issue "resolution" was posted by me in my "What Casio told me!" Thread.

We need to wait for OS 3.04 to come out to fix a number of bugs.

hellas1



thanks - I guess I'm in a hurry to get involved. I'll sit back a bit more and get to know the board a bit better before I go jumping in next time! :-)




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