Singular Manual: Atkin

| #### D.12.2.14 Atkin Procedure from library `atkins.lib` (see atkins_lib). Return: 1, if N is prime, -1, if N is not prime, 0, if the algorithm is not applicable, since there are too few discriminants Assume: N is coprime to 6 and different from 1 Note: K/2 is input for the procedure "disc", K is input for the procedure "HilbertClassPoly", B describes the number of recursions being calculated. The basis of the algorithm is the following theorem: Let N be an integer coprime to 6 and different from 1 and E be an ellipic curve modulo N. Assume that we know an integer m and a point P of E(Z/NZ) satisfying the following conditions. (1) There exists a prime divisor q of m such that q > (4-th root(N)+1)^2. (2) m*P = O(E) = (0:1:0). (3) (m/q)*P = (x:y:t) with t element of (Z/NZ)*. Then N is prime. Example:
    LIB "atkins.lib";
    ring R = 0,x,dp;
    Atkin(7691,100,5);
    ==> -1
    Atkin(3473,10,2);
    ==> -1
    printlevel=1;
    Atkin(10000079,100,2);
    ==> Set i = 0, n = 0 and N(i) = N(0)= 10000079.
    ==> pause>
    ==> List H of possibly suitable discriminants will be calculated.
    ==> H = -3,-4,-7,-8,-11,-12,-15,-16,-19,-20,-23,-24,-27,-28,-31,-32,-35,-36,-\
       39,-40,-43,-44,-47,-48,-51,-52,-55,-56,-59,-60,-63,-64,-67,-68,-71,-72,-7\
       5,-76,-79,-80,-83,-84,-87,-88,-91,-92,-95,-96,-99,-100,-103,-104,-107,-10\
       8,-111,-112,-115,-116,-119,-120,-123,-124,-127,-128,-131,-132,-135,-136,-\
       139,-140,-143,-144,-147,-148,-151,-152,-155,-156,-159,-160,-163,-164,-167\
       ,-168,-171,-172,-175,-176,-179,-180,-183,-184,-187,-188,-191,-192,-195,-1\
       96,-199,-200
    ==> pause>
    ==> N(0) = 10000079 is divisible by 5.
    ==> pause>
    ==> N(0) = N = 10000079 and therefore N is not prime.
    ==> pause>
    ==> -1

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