Post new topic Reply to topic  [ 3 posts ] 
Author Message
 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!


Report this post
Top
 Profile  
Reply with quote  
 Post subject: Re: A "syntax"/notation problem
PostPosted: Thu Jan 16, 2014 6:47 pm 

Joined: Wed Mar 03, 2010 5:08 pm
Posts: 108
Location: Germany, Münster
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.


Report this post
Top
 Profile  
Reply with quote  
 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


Report this post
Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

It is currently Fri May 13, 2022 10:56 am
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group