Difference between symbolic and numeric calculation on imaginary unit

Difference between symbolic and numeric calculation on imaginary unit - Expression (1/i)*(1/i) , symbolic result "1", numeric result "-1" - Сообщения

#1 Опубликовано: 13 лет назад
Gossage

Gossage

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Hello,

I try to calculate "(1/i)*(1/i)" either in symbolic and numeric method and I get "1" and "-1" respectively.

Note that this problem does not appear with the expression "(1/i^2)".

In attachment a simple .sm file to illustrate the bug.

Best regards,
Gossage
bug_imag.sm (2 КиБ) скачан 111 раз(а).
#2 Опубликовано: 13 лет назад
Radovan Omorjan

Radovan Omorjan

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Hello Gossage,

I just can confirm this.
Have no explanation of this, except that this is definitely a bug.

Regards,
Radovan
When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"
#3 Опубликовано: 13 лет назад
Diego Jarrín

Diego Jarrín

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There are other problems with the symbolic interpretation.
Did you tried to compute sin(-4*pi/3) and sin(2*pi/3) in the numeric and symbolic methods?
symbolictrouble.sm (17 КиБ) скачан 124 раз(а).
Ecuadorian Electronic engineer and MBA student at Salesian Polytechnic University.
#4 Опубликовано: 13 лет назад
Martin Kraska

Martin Kraska

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Hi

These examples just illustrate the known fact that the SMath symbolic engine is unreliable. Currently, it is not safe to use it. The Numeric engine seems to be more reliable, thus it's usage can be recommended.

What to do if you need symbolic calculations? There is a plugin that communicates with a dos version of maple and is much more powerful than the SMath internal engine. However, the plugin is not localization-safe, i.e. if argument delimiter is set to semicolon ;

I would like SMath to be an 2D document interface to maxima, which has all the math (including units) one would need but lacks the MathCad like document interface.

Best regards, MK
Martin Kraska Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx
#5 Опубликовано: 12 лет назад
Andrey Ivashov

Andrey Ivashov

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Fixed.
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Radovan Omorjan 12 лет назад
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