Added function for getting a specific fibonacci num

src/Algorithms.rs

@@ -39,6 +39,44 @@ pub fn getAllFibBig(goalNumber: num::BigInt) -> Vec<num::BigInt>{
 	fibNums.remove(fibNums.len() - 1);
 	return fibNums;
 }
+//This function returns all the divisors of goalSubscript
+pub fn getFib(goalSubscript: i64) -> i64{
+	//Setup the variables
+	let mut fibNums = [1, 1, 0];
+
+	//If the number is <= 0 return 0
+	if(goalSubscript <= 0){
+		return 0;
+	}
+
+	//Loop through the list, generating Fibonacci numbers until it finds the correct subscript
+	let mut fibLoc = 2;
+	while(fibLoc < goalSubscript){
+		fibNums[(fibLoc % 3) as usize] = fibNums[((fibLoc - 1) % 3) as usize] + fibNums[((fibLoc - 2) % 3) as usize];
+		fibLoc += 1;
+	}
+	//Return the proper number. The location counter is 1 off of the subscript
+	return fibNums[((fibLoc - 1) % 3) as usize];
+}
+pub fn getFibBig(goalSubscript: num::BigInt) -> num::BigInt{
+	//Setup the variables
+	let mut fibNums = [num::BigInt::from(1), num::BigInt::from(1), num::BigInt::from(0)];
+
+	//If the number is <= 0 return 0
+	if(goalSubscript <= num::BigInt::from(0)){
+		return num::BigInt::from(0);
+	}
+
+	//Loop through the list, generating Fibonacci numbers until it finds the correct subscript
+	let mut fibLoc = 2;
+	while(num::BigInt::from(fibLoc) < goalSubscript){
+		fibNums[(fibLoc % 3) as usize] = &fibNums[((fibLoc - 1) % 3) as usize] + &fibNums[((fibLoc - 2) % 3) as usize];
+		fibLoc += 1;
+	}
+	//Return the proper number. The location counter is 1 off of the subscript
+	let temp = &fibNums[((fibLoc - 1) % 3) as usize];
+	return num::BigInt::new(temp.to_u32_digits().0, temp.to_u32_digits().1);
+}
 
 //This function returns all factors of goalNumber
 pub fn getFactors(mut goalNumber: i64) -> Vec<i64>{

src/lib.rs

@@ -36,6 +36,25 @@ mod AlgorithmsTests{
 		assert_eq!(correctAnswerBig, answerBig);
 	}
 	#[test]
+	fn testGetFib(){
+		//Test1
+		let correctAnswer1 = 144;
+		let number1 = 12;
+		let answer1 = super::Algorithms::getFib(number1);
+		assert_eq!(correctAnswer1, answer1);
+		//Test2
+		let correctAnswer2 = 6765;
+		let number2 = 20;
+		let answer2 = super::Algorithms::getFib(number2);
+		assert_eq!(correctAnswer2, answer2);
+
+		//Test3
+		let correctAnswer3 = "1070066266382758936764980584457396885083683896632151665013235203375314520604694040621889147582489792657804694888177591957484336466672569959512996030461262748092482186144069433051234774442750273781753087579391666192149259186759553966422837148943113074699503439547001985432609723067290192870526447243726117715821825548491120525013201478612965931381792235559657452039506137551467837543229119602129934048260706175397706847068202895486902666185435124521900369480641357447470911707619766945691070098024393439617474103736912503231365532164773697023167755051595173518460579954919410967778373229665796581646513903488154256310184224190259846088000110186255550245493937113651657039447629584714548523425950428582425306083544435428212611008992863795048006894330309773217834864543113205765659868456288616808718693835297350643986297640660000723562917905207051164077614812491885830945940566688339109350944456576357666151619317753792891661581327159616877487983821820492520348473874384736771934512787029218636250627816".parse::<num::BigInt>().unwrap();
+		let number3 = num::BigInt::from(4782);
+		let answer3 = super::Algorithms::getFibBig(number3);
+		assert_eq!(correctAnswer3, answer3);
+	}
+	#[test]
 	fn testGetPrimes(){
 		//Test1
 		let mut correctAnswer1 = Vec::<i64>::new();