Difference between revisions of "HowTo:Use Modular Numbers"

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The creation of a polynomial ring with no indeterminated has been disabled to highlight this (unexpected?) behaviour.
 
The creation of a polynomial ring with no indeterminated has been disabled to highlight this (unexpected?) behaviour.
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by [[User:Bigatti|Bigatti]] 17:26, 29 Nov 2005 (CET)
  
 
[[Category:HowTo]][[Category:CoCoA4]]
 
[[Category:HowTo]][[Category:CoCoA4]]

Revision as of 18:26, 29 November 2005

Question

How can one compute with modular numbers? What's wrong in this?

  Use R::=Z/(5)[x];
  5x+2y;
2y
-------------------------------
  5=0;
FALSE
-------------------------------

Moreover this command throws an error

  Use R::=Z/(5);

Answer

  Type(5);
INT
-------------------------------

5 is an integer, and integers do not depend on the current ring: could you imagine what would happen to a For cycle over Z/(2)? ;-)

If you want to use 5 as a modular number you should either use this syntax (similar to C/C++)

  5 % 5;
0 % 5
-------------------------------

or embed your integer into the polynomial ring

  Use R::=Z/(5)[x];
  Poly(5);
0
-------------------------------

The creation of a polynomial ring with no indeterminated has been disabled to highlight this (unexpected?) behaviour.

by Bigatti 17:26, 29 Nov 2005 (CET)