Units

Units - Сообщения

#1 Опубликовано: 23.04.2012 12:01:54
László Radnay

László Radnay

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Hello!

I have problem vith the units. I already have several smath file that I made with one of the previous versions. By recalculating these with the use of the latest version, there are a lot of mistakes, and it doesent works at all. Maybe because by me the new version makes strange simplifications by units. It cant add the proviously calculated "s*1" (secundum multiplied with one) and for example "s^1".

An other strange thing is that sometimes (when trigonometrics or roots are in the equation)

For example A:=equation

I got different results for: A= and equation=

If you can, please help me. Sorry for my bad english.

L.R.
#2 Опубликовано: 23.04.2012 13:13:28
Andrey Ivashov

Andrey Ivashov

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Radnay, please send file(s) to me and I will check the reason of the errors you've mentioned.

Best regards.
#3 Опубликовано: 24.04.2012 04:20:24
László Radnay

László Radnay

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Hello!

I don't know, where to send it.
Maybe it will work if you can download the smath file from http://www.mfk.unideb.hu/userdir/laszlo.radnay/smatherror.sm
and the pdf form from http://www.mfk.unideb.hu/userdir/laszlo.radnay/smatherror.pdf.

Best Regards
#4 Опубликовано: 24.04.2012 04:57:21
Radovan Omorjan

Radovan Omorjan

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Hello,

I tried the *.sm file and this time Numeric and None optimization will fail complaining about unmatching units. Symbolic optimization will give the results.



If we assign the expression to the variable RES here, only the Symbolic optimization will give the result. Numeric and None will fail.

Regards,
Radovan
When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"
#5 Опубликовано: 24.04.2012 05:32:30
László Radnay

László Radnay

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Hi!

I have tried, what you say and it works in this case.

But, with the same settings an other one doesent works.

http://www.mfk.unideb.hu/userdir/laszlo.radnay/error2.sm

The errors are on the 4. ,5. ,8. page. I cant understand it.

L.R.
#6 Опубликовано: 24.04.2012 05:50:27
Radovan Omorjan

Radovan Omorjan

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Hello,

I have no idea what has going on, sorry. This might be some kind of a bug.
For instance, this is an error from your file:



Do not even know what was the error about. What actually "1E" means?

Andrey is the only one who can give the right answer.

Regards,
Radovan
When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"
#7 Опубликовано: 24.04.2012 06:11:44
László Radnay

László Radnay

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Hi!

I'm glad that I could at least describe my problem.

This file worked properly half year ago, with the actual version.

I look forward for your help.

L.R.
#8 Опубликовано: 24.04.2012 07:37:50
László Radnay

László Radnay

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Here I am again.

http://www.mfk.unideb.hu/userdir/laszlo.radnay/smatherror.sm

In this I have made the changes that you recommended Radovan. I had to modify the datas to show this:

In the bottom of the page I have calculated the value of "A" on the basis of the datas, calculated by the program previously.

The results are different.

This is the other thing I have mentioned in my first comment.

L.R.
#9 Опубликовано: 24.04.2012 09:13:43
Radovan Omorjan

Radovan Omorjan

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Hello Radnay,

I just have to repeat that there are obviously some problems in the SMath calculations regarding your examples. It is good that you found this and reported it as well.
I also know that Andrey will answer on this and find what the problem was as soon as he can.

Regards,
Radovan
When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"
#10 Опубликовано: 24.04.2012 17:35:37
Andrey Ivashov

Andrey Ivashov

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I would classify this as a bug. Will fix it. Thanks.

Best regards, Andrey Ivashov.
#11 Опубликовано: 29.04.2012 00:03:53
studoc

studoc

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Hi guys,

On the subject of units, I need a little prod...
Smath fastracks a lot of high end maths, I must concede though all of my stuff is low brow and my use of the program directed at formalising repetitive tasks (this the program also does well...!)

The units confound me though....

The program can ignore the units I have used and substitute it's own.

Can I convert the answer into the units I want....?

cheers,

Stu.
#12 Опубликовано: 29.04.2012 01:47:59
Radovan Omorjan

Radovan Omorjan

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Hello Stu,
Wrote

The program can ignore the units I have used and substitute it's own.

Can I convert the answer into the units I want....?


Yes, you can. See for example this tutorial please, Equations and Units starting from page 5.

Regards,
Radovan
When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"
#13 Опубликовано: 29.04.2012 06:18:23
studoc

studoc

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Thanks for that Radovan, just the sort of thing I needed...
I do get some interesting results, including the original units, in my answer though...
For this time it's far easier to enter the units as text only, i'll keep this info handy and endeavour incorporate it in the next project...

thanks...!

Stu.
#14 Опубликовано: 29.04.2012 06:39:26
Radovan Omorjan

Radovan Omorjan

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You are welcome, Stu,
Wrote

I do get some interesting results, including the original units, in my answer though...
For this time it's far easier to enter the units as text only, i'll keep this info handy and endeavour incorporate it in the next project...


If you find something that does look suspicious or problematic to you regarding units, just report it. That might be a bug and all of us will be grateful to you if you find one. The user feedback is very important to SMath project, especially reported possible bugs in order to get fixed.

Regards,
Radovan
When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"
#15 Опубликовано: 16.05.2012 23:28:28
studoc

studoc

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Hi,

Having another look at this, don't know if it's so much a possible bug, as much as my lack of understanding, but it grinds me to a halt...

I looked through your link and am relying on the last section (complex conversions) to reliably establish my units (tick that box), but the calculation.....

If we consider that weight equals mass times acceleration due to gravity,
vis.
W=mg

I can declare the units of mass as, "kg" and the units of acceleration due to gravity as, "m/s^2", but when I enter, "W=" there is no result... Hovering over the expression shows the message, "operation cannot be performed with units", but we all know the units are, "N".

In a simple example, this is the sort of thing I am endeavouring to straighten out, can I.....?

cheers,

Stu.
#16 Опубликовано: 17.05.2012 04:40:56
Radovan Omorjan

Radovan Omorjan

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Hello Stu,

I did not quite understand you, sorry. But Here is a simple example:
Simple example with units

Pay attention the black and blue variables. Blue variables are "units" and they are different from the black variables with the same name. I used (above the separation line) "g" but this is apredefined variable inside the unit SMath system - therefore is in blue color. Below the line I used "g" as a variable in SMtah and then represented "W" in different units. Just click on it and start typing. The Dynamic assistnce will show you the list and you can choose the desired one (by TAB or double click on it)

Example with changing units

Regards,
Radovan
When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"
#17 Опубликовано: 17.05.2012 13:16:42
Andrey Ivashov

Andrey Ivashov

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The initial issue fixed:



Regards.
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Radovan Omorjan 17.05.2012 15:08:00
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