Added function to test if an integer is prime

Algorithms.lua

@@ -119,6 +119,21 @@ function getNumPrimes(numberOfPrimes)
 	return primes;
 end
 
+--This function determines whether the number passed into it is a prime
+function isPrime(possiblePrime)
+	if(possiblePrime <= 3) then
+		return possiblePrime > 1;
+	elseif(((possiblePrime % 2) == 0) or ((possiblePrime % 3) == 0)) then
+		return false;
+	end
+	for cnt = 5, math.sqrt(possiblePrime), 6 do
+		if(((possiblePrime % cnt) == 0) or ((possiblePrime % (cnt + 2)) == 0)) then
+			return false;
+		end
+	end
+	return true;
+end
+
 --This is a function that returns all the factors of goalNumber
 function getFactors(goalNumber)
 	local primes = getPrimes(math.ceil(math.sqrt(goalNumber)));	--Get all the primes up the largest possible divisor

testAlgorithms.lua

@@ -1,7 +1,7 @@
 --lua/luaClasses/testAlgorithms.lua
 --Mathew Ellison
 -- Created: 03-28-19
---Modified: 06-29-21
+--Modified: 06-30-21
 --This script is used to test the Algorithms script
 --[[
 	Copyright (C) 2021  Matthew Ellison
@@ -64,6 +64,52 @@ local function testGetNumPrimes()
 	end
 end
 
+local function testIsPrime()
+	local failed = false;	--Holds whether a test was failed
+
+	--Test 1
+	local num = 2;
+	local correctAnswer = true;
+	local answer = isPrime(num);
+	--Print an error message if the function returned the wrong answer
+	if(correctAnswer ~= answer) then
+		io.write("isPrime failed the first test\n");
+		failed = true;
+	end
+	--Test 2
+	num = 97;
+	correctAnswer = true;
+	answer = isPrime(num);
+	--Print an error message if the function returned the wrong answer
+	if(correctAnswer ~= answer) then
+		io.write("isPrime failed the second test\n");
+		failed = true;
+	end
+	--Test 3
+	num = 1000;
+	correctAnswer = false;
+	answer = isPrime(num);
+	--Print an error message if the function returned the wrong answer
+	if(correctAnswer ~= answer) then
+		io.write("isPrime failed the third test\n");
+		failed = true;
+	end
+	--Test 4
+	num = 1;
+	correctAnswer = false;
+	answer = isPrime(num);
+	--Print an error message if the function returned the wrong answer
+	if(correctAnswer ~= answer) then
+		io.write("isPrime failed the fourth test\n");
+		failed = true;
+	end
+
+	--Print a message if all of the tests passed
+	if(not failed) then
+		io.write("isPrime passed all tests\n");
+	end
+end
+
 local function testGetFactors()
 	local failed = false;	--Holds whether a test was failed
 
@@ -458,6 +504,12 @@ testGetNumPrimes();
 timer:stop();
 io.write("It took " .. timer:getString() .. " to run this test\n");
 
+--Test isPrime
+timer:start();
+testIsPrime();
+timer:stop();
+io.write("It took " .. timer:getString() .. " to run this test\n");
+
 --Test getFactors
 timer:start();
 testGetFactors();