Algorithms And Data Structures

Download e-book for kindle: Algorithms For Modular Elliptic Curves by J. E. Cremona

By J. E. Cremona

ISBN-10: 0521598206

ISBN-13: 9780521598200

Elliptic curves are of vital and becoming value in computational quantity concept, with a number of purposes in such components as cryptography, primality trying out and factorisation. This ebook, now in its moment version, provides a radical remedy of many algorithms about the mathematics of elliptic curves, with feedback on computing device implementation. it really is in 3 components. First, the writer describes intimately the development of modular elliptic curves, giving an particular set of rules for his or her computation utilizing modular symbols. Secondly a set of algorithms for the mathematics of elliptic curves is gifted; a few of these haven't seemed in ebook shape sooner than. They comprise: discovering torsion and non-torsion issues, computing heights, discovering isogenies and classes, and computing the rank. eventually, an intensive set of tables is supplied giving the result of the author's implementation of the algorithms. those tables expand the generally used 'Antwerp IV tables' in methods: the diversity of conductors (up to 1000), and the extent of aspect given for every curve. specifically, the amounts in terms of the Birch Swinnerton-Dyer conjecture were computed in each one case and are incorporated. All researchers and graduate scholars of quantity concept will locate this booklet beneficial, relatively these attracted to the computational facet of the topic. That element will make it attraction additionally to laptop scientists and coding theorists.

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Extra resources for Algorithms For Modular Elliptic Curves

Example text

Tricks and shortcuts. In fact, the data l+ and m+ can be computed earlier in the first H + (N ) phase, since they only depend on the real projection of the period lattice. Hence we can already compute the real period x from the data we have from the first phase. Moreover, it is easy to find a suitable prime l− once we know the Hecke eigenvalues of f , by numerically computing P (l, f ) for several primes l ≡ −1 (mod 4) until we find a value which is clearly non-zero. It follows that the only purpose of the extremely expensive second phase of the computation, working in H(N ), is to determine the integer factor m− and the type of the lattice.

Thus, once we know ap and n(p, f ) for a single prime p, we can evaluate the rational number L(Ef , 1)/Ω(Ef ), whose value is predicted by the Birch–Swinnerton-Dyer conjecture for Ef . In particular, we should have L(f, 1) = 0 if and only if Ef (Q) is infinite. In the tables we give the value of L(f, 1)/Ω(f ) for each rational newform f computed, and observe that the value is consistent with the Birch–Swinnerton-Dyer conjecture in each case. 10) for a single prime p, we may (if L(f, 1) = 0) use the fact that n(p, f )/(1 + p − ap ) is independent of p to compute the eigenvalue ap quickly for other p, by computing n(p, f ).

1) in terms of the generating M-symbols and projecting onto each eigenspace. 1) need only be computed once. The Hecke eigenvalues which we have computed are stored in a data file for use both in subsequent steps of the calculations at level N , and also as part of the cumulative database which will be accessed when levels which are multiples of N are reached. The exact number of ap needed depends on N , and on the form f , and will not be known until the numerical calculation of periods is carried out in the next phase.

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Algorithms For Modular Elliptic Curves by J. E. Cremona


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