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 Post subject: A "syntax"/notation problem
PostPosted: Thu Jan 16, 2014 10:46 am 

Joined: Mon Jun 29, 2009 1:51 pm
Posts: 20
Version 3-1-6 gives me:
> 3x^2-3*x^2;
6x2

(And of course this difference between 3x^2 and 3*x^2 influences other computations, e.g. Milnor number etc.)
It is difficult to always remember, especially if one works with other computer systems. Could you correct this in the future version?

Thanks!


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 Post subject: Re: A "syntax"/notation problem
PostPosted: Thu Jan 16, 2014 6:47 pm 

Joined: Wed Mar 03, 2010 5:08 pm
Posts: 103
Location: Germany,
Dmitry wrote:
Version 3-1-6 gives me:
> 3x^2-3*x^2;
6x2

Singular interprets 3x^2 as (3x)^2 which is 9*x^2, then the result 6x2 follows

Everything left from the ^ upto an * or + or - is taken as one token,
thus e.g. 2x2y^3 is 8*x^6*y^3;

Certainly a user should know this behaviour
but it seems to be a bit hidden in the manual.
Sadly, it is not stated precisely in the Getting started part:
http://www.singular.uni-kl.de/Manual/la ... .htm#SEC13

But see Section
6.4 Miscellaneous oddities
2. monomials and precedence
http://www.singular.uni-kl.de/Manual/3-1-6/sing_458.htm

To remember:
If the variable names consist only of single letters,
Singular allows to omit the * for the multiplication.
If one do so, then also one don't use the caret ^ for the exponentiation.

Conversely, if you use the long version with ^, then you should put the *, too.


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 Post subject: Re: A "syntax"/notation problem
PostPosted: Sun Jan 19, 2014 8:17 am 

Joined: Mon Jun 29, 2009 1:51 pm
Posts: 20
ok, thanks :D


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