[Scilab-users] expression block in xcos gives “answer given for scilab expression is wrong” error

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farimani farimani
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[Scilab-users] expression block in xcos gives “answer given for scilab expression is wrong” error

As I have originally explained in  this post
<https://stackoverflow.com/questions/54756985/expression-block-in-xcos-gives-answer-given-for-scilab-expression-is-wrong-err>  
I'm trying to put the SciLab expression:

sign(u2 – u1) * (2 * ((Fm + M) * abs(u2 – u1) + k * (u2^2 – u1^2) / 2) /
m)^0.5

but I get this error message:

<http://mailinglists.scilab.org/file/t497909/7ivdz.png>

answer given for scilab expression is incorrect...

I would appreciate if you could help me know what is the problem and how I
can solve it. Maybe I should use a different block?





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Samuel GOUGEON Samuel GOUGEON
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Re: expression block in xcos gives “answer given for scilab expression is wrong” error

Hello Farimani,

Le 19/02/2019 à 10:47, farimani a écrit :
As I have originally explained in  this post
<https://stackoverflow.com/questions/54756985/expression-block-in-xcos-gives-answer-given-for-scilab-expression-is-wrong-err>  
I'm trying to put the SciLab expression:

sign(u2 – u1) * (2 * ((Fm + M) * abs(u2 – u1) + k * (u2^2 – u1^2) / 2) /
m)^0.5

but I get this error message:

<http://mailinglists.scilab.org/file/t497909/7ivdz.png> 

answer given for scilab expression is incorrect...

I would appreciate if you could help me know what is the problem and how I
can solve it. Maybe I should use a different block?

Copy/pasting your formula in the console:
[Fm, M, m, k] = (1,1,1,1);
[u1, u2] = (1,2);
r = sign(u2  u1) * (2 * ((Fm + M) * abs(u2  u1) + k * (u2^2  u1^2) / 2) /m)^0.5;

--> r = sign(u2 – u1) * (2 * ((Fm + M) * abs(u2 – u1) + k * (u2^2 – u1^2) / 2) /m)^0.5;
r = sign(u2 – u1) * (2 * ((Fm + M) * abs(u2 – u1) + k * (u2^2 – u1^2) / 2) /m)^0.5;
            ^~~^
Error: syntax error, unexpected identifier, expecting "," or )

Puzzling... Hard to find why, but finally:

You have likely copy/pasted this formula from a "formatted" document, maybe a web site, etc.
Then, the included "–" character is not the mathematical minus, that is "-".
This puzzles the Scilab's parser.

If you input the same formula, just replacing the hyphens with the true minus, it works,
in the console as well as in Xcos.

--> r = sign(u2 - u1) * (2 * ((Fm + M) * abs(u2 - u1) + k * (u2^2 - u1^2) / 2) /m)^0.5
 r  =
   2.6457513

HTH
Samuel


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