Added the first problems for ProjectEuler.net

ProjectEuler/Problem3.m

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+%ProjectEuler/Problem3.m
+%This is a script to answer Problem 3 for Project Euler
+%The largest prime factor of 600851475143
+
+%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
+%number = 16;	%Used for a test case
+
+%Get the prime numbers up to sqrt(number). If it is not prime there must be a value <= sqrt
+primeNums = primes(sqrt(number));
+
+%Setup the loop
+counter = 1;
+%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))
+
+	%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
+end
+%When the last number is not divisible by a prime number it must be a prime number
+factors(end + 1) = tempNum;
+
+%Remove the variables
+clear counter;
+clear tempNum;
+clear answer;
+clear number;
+clear primeNums;
+
+%Print the answer
+max(factors)