Previous Page Next Page Contents

numlib::ecm -- factor an integer using the elliptic curve method

Introduction

numlib::ecm(n) tries to factor the positive integer n using the elliptic curve method.

numlib::ecm(n, BaseBound, s, Step2Bound) and numlib::ecm(n, Base, s, Step2Bound) do the same, with some internal parameters of the algorithm specified - see the ``Details'' section. The last, or the last two, parameter(s) may be omitted.

Call(s)

numlib::ecm(n)
numlib::ecm(n, BaseBound)
numlib::ecm(n, Base)
numlib::ecm(n, BaseBound, s)
numlib::ecm(n, Base, s)
numlib::ecm(n, BaseBound, s, Step2Bound)
numlib::ecm(n, Base, s, Step2Bound)

Parameters

n - positive integer
BaseBound - positive integer
Base - list of primes
s - integer
Step2Bound - positive integer

Returns

numlib::ecm returns an integer that divides n; the return value may equal 1 or n.

Related Functions

ifactor

Details

Example 1

We factor an integer using the default parameters.

>> numlib::ecm(10000019070000133)
                                 10000019

Example 2

If too few multiplications on the elliptic curve are carried out, the algorithm is likely to fail.

>> numlib::ecm(10000019070000133, 50)
                                     1

Background

Changes




Do you have questions or comments?


Copyright © SciFace Software GmbH & Co. KG 2000