Gcd( r1, r2... )
Gcd( R, r1, r2... )
In the first form Gcd
returns the greatest common divisor of the ring
elements r1, r2... etc. in their default ring (see DefaultRing).
In the second form Gcd
returns the greatest common divisor of the ring
elements r1, r2... etc. in the ring R. R must be a Euclidean
ring (see IsEuclideanRing) so that QuotientRemainder
(see
QuotientRemainder) can be applied to its elements. Gcd
returns the
standard associate (see StandardAssociate) of the greatest common
divisors.
A greatest common divisor of the elements r_1, r_2... etc. of the ring R is an element of largest Euclidean degree (see EuclideanDegree) that is a divisor of r_1, r_2... etc. We define gcd( r, 0_R ) = gcd( 0_R, r ) = StandardAssociate( r ) and gcd( 0_R, 0_R ) = 0_R.
gap> Gcd( Integers, 123, 66 ); 3
Gcd
calls R.operations.Gcd
repeatedly, each time passing the result
of the previous call and the next argument, and returns the value of the
last call.
The default function called this way is RingOps.Gcd
, which applies the
Euclidean algorithm to compute the greatest common divisor. Special
categories of rings overlay this default function with more efficient
functions.
GAP 3.4.4