problem with the solve function

problem with the solve function - Сообщения

#1 Опубликовано: 08.04.2009 12:33:14
scb

scb

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Thank you for a great program, which I am beginning to learn to use. But I have come upon a problem trying to solve a rather simple equation: x^6 - 6 = 9. Using either one of the two methods I correctly get two roots, of which the first is correct, i.e: 1,5704, but the other is -3,1629 which is obviously wrong.
I am using the program on a Dell Axim x51v in main memory.
Another issue: is there a manual somewhere, or do we have to learn to use the program by doing calculations with it ?

Yours

scb
#2 Опубликовано: 08.04.2009 13:37:44
Andrey Ivashov

Andrey Ivashov

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Hello.

Wrote

Using either one of the two methods I correctly get two roots, of which the first is correct, i.e: 1,5704, but the other is -3,1629 which is obviously wrong.


I've tried your example and didn't find any observations. Here is a pic:

Please, describe here, what should I do to get such wrong answer as you figured out.

Wrote

Another issue: is there a manual somewhere, or do we have to learn to use the program by doing calculations with it ?


Unfortunately yes. SMath Studio has no any Manual yet. I can just advise you to take a look to the SMath Studio Samples Forum for the first steps.
#3 Опубликовано: 08.04.2009 14:51:53
scb

scb

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I am using the Handheld version on my Dell Axim x51v, could there be a problem solely with the PDA version (WM5) ?
Yours
scb
#4 Опубликовано: 08.04.2009 15:55:25
Andrey Ivashov

Andrey Ivashov

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I've checked your example on my device - no problems.
Are you using SMath Studio 0.78?
#5 Опубликовано: 08.04.2009 16:31:51
scb

scb

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I'm using 0.78, but I will try reinstalling and let you know.
#6 Опубликовано: 08.04.2009 17:10:30
scb

scb

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Well, I tried to download your program again and reinstall, and this seems to have solved the problem.
#7 Опубликовано: 22.04.2009 06:43:36
scb

scb

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I've looked into this again, and I've found, that if I change the roots range in options from "-20 to +20" to "-100 to +100" I can reproduce the answer I first came up with : 1,5704 and -3,1629. Is this wrong using of the solve function ???
#8 Опубликовано: 03.08.2009 10:14:03
gimmick

gimmick

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Here's the same results from Maxima and Wolfram Alpha.



#9 Опубликовано: 03.08.2009 11:31:59
Radovan Omorjan

Radovan Omorjan

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Wrote

I've looked into this again, and I've found, that if I change the roots range in options from "-20 to +20" to "-100 to +100" I can reproduce the answer I first came up with : 1,5704 and -3,1629. Is this wrong using of the solve function ???



You are right scb. Here is the result in v0.82

This must be a bug?

In addition, gimmick gave the "solve" but in wellknown Symbolic engines like Maxima and Mathematica which gives both real and complex results. Unfortunately, Solve in SMath is a numerical (not symbolical) routine and tries to find only real roots numerically (result are real numbers not expressions). Actually, if you would try to solve this symbolically you will get this?


Regards,
Radovan
When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"
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