From d8a77a926657201e60ad171155145d40ab6192d8 Mon Sep 17 00:00:00 2001
From: Mattrixwv <m_ellison@ymail.com>
Date: Thu, 29 Oct 2020 08:43:06 -0400
Subject: [PATCH] Updated problem 3 algorithm

---
 Problem3.m | 70 ++++++++++++++----------------------------------------
 1 file changed, 18 insertions(+), 52 deletions(-)

diff --git a/Problem3.m b/Problem3.m
index 1c06c44..70437aa 100644
--- a/Problem3.m
+++ b/Problem3.m
@@ -1,10 +1,11 @@
+function [] = Problem3
 %ProjectEuler/Octave/Problem3.m
 %Matthew Ellison
-% Created: 
-%Modified: 03-28-19
+% Created: 03-28-19
+%Modified: 10-28-20
 %The largest prime factor of 600851475143
 %{
-	Copyright (C) 2019  Matthew Ellison
+	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
@@ -21,63 +22,28 @@
 %}
 
 
-%Setup your variables
-number = 600851475143;	%The number we are trying to find the greatest prime factor of
-primeNums = [];	%A list of prime numbers. Will include all prime numbers <= number
-factors = [];	%For the list of factors of number
-tempNum = number;	%Used to track the current value if all of the factors were taken out of number
+	%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));
+	%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();
+	%Start the timer
+	startTime = clock();
 
-%Setup the loop
-counter = 1;
+	factors = factor(600851475143);
 
-%Start with the lowest number and work your way up. When you reach a number > size(primeNums) you have found all of the factors
-while(counter <= size(primeNums)(2))
+	%Stop the timer
+	endTime = clock();
 
-	%Divide the number by the next prime number in the list
-	answer = (tempNum/primeNums(counter));
-
-	%If it is a whole number add it to the factors
-	if(mod(answer,1) == 0)
-		factors(end + 1) = primeNums(counter);
-		%Set tempNum so that it reflects number/factors
-		tempNum = tempNum / primeNums(counter);
-		%Keep the counter where it is in case a factor appears more than once
-		%Get the new set of prime numbers
-		primeNums = primes(sqrt(tempNum));
-	else
-		%If it was not an integer increment the counter
-		++counter;
-	end
+	%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
-%When the last number is not divisible by a prime number it must be a prime number
-factors(end + 1) = tempNum;
-
-%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))
-
-%Cleanup your variables
-clear counter;
-clear tempNum;
-clear answer;
-clear number;
-clear primeNums;
-clear factors;
-clear startTime;
-clear endTime;
-clear ans;
 
 %{
 Results:
 The largest prime factor of 600851475143 is 6857
-It took 0.006256 seconds to run this algorithm
+It took 0.005714 seconds to run this algorithm
 %}