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ModuleDen

Returns the denominator of the given module.

Syntax:

den := ModuleDen(M);

integer
  den  
module
  M  

Description:

The denominator of a module M is defined as the smallest natural number d that the module dM is an integral module. An integral module over the Dedekind ring R is a subset of R^n where n is the degree of the module.


Example:

kash>  O := OrderMaximal(Poly(Zx,[1, 5, -6, -53, 3, 206, 244]));;
kash> Ids:=[ Ideal(5, Elt(O,[-27, 1, -2, 1, -3, 15])),
> Ideal(1, Elt(O,[-18, 0, -3, 3, -1, 0]/5)) ];
[ <5, [-27, 1, -2, 1, -3, 15]>, <1, [-18, 0, -3, 3, -1, 0] / 5> ]
kash> M := Module(Ids,Mat(O,[[1,2],[2,1]])/15);
{<5, [-27, 1, -2, 1, -3, 15]><1, [-18, 0, -3, 3, -1, 0] / 5>
[1 / 15 2 / 15]
[2 / 15 1 / 15]
}

kash> ModuleDen(M);
> 75


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