function [] = Problem3 %ProjectEuler/Octave/Problem3.m %Matthew Ellison % Created: 03-28-19 %Modified: 10-28-20 %The largest prime factor of 600851475143 %{ Copyright (C) 2020 Matthew Ellison This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see . %} %Setup your variables number = 600851475143; %The number we are trying to find the greatest prime factor of factors = []; %For the list of factors of number %Get the prime numbers up to sqrt(number). If it is not prime there must be a value <= sqrt primeNums = primes(sqrt(number)); %Start the timer startTime = clock(); factors = factor(600851475143); %Stop the timer endTime = clock(); %Print the results printf("The largest prime factor of 600851475143 is %d\n", max(factors)) printf("It took %f seconds to run this algorithm\n", etime(endTime, startTime)) end %{ Results: The largest prime factor of 600851475143 is 6857 It took 0.005714 seconds to run this algorithm %}