greatest-common-divisor

Java: get greatest common divisor

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I have seen that such a function exists for BigInteger , i.e. BigInteger#gcd . Are there other functions in Java which also work for other types ( int , long or Integer )? It seems this would make sense as java.lang.Math.gcd (with all kinds of overloads) but it is not there. Is it somewhere else? (Don't confuse this question with "how do I implement this myself", please!) Tony Ennis For int and long, as primitives, not really. For Integer, it is possible someone wrote one. Given that BigInteger is a (mathematical/functional) superset of int, Integer, long, and Long, if you need to use these

Numpy gcd function

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问题 Does numpy have a gcd function somewhere in its structure of modules? I'm aware of fractions.gcd but thought a numpy equivalent maybe potentially quicker and work better with numpy datatypes. I have been unable to uncover anything on google other than this link which seems out of date and I don't know how I would access the _gcd function it suggests exists. Naively trying: np.gcd np.euclid hasn't worked for me... 回答1: You can write it yourself: def numpy_gcd(a, b): a, b = np.broadcast_arrays

Euclidean greatest common divisor for more than two numbers

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问题 Can someone give an example for finding greatest common divisor algorithm for more than two numbers? I believe programming language doesn't matter. 回答1: Start with the first pair and get their GCD, then take the GCD of that result and the next number. The obvious optimization is you can stop if the running GCD ever reaches 1. I'm watching this one to see if there are any other optimizations. :) Oh, and this can be easily parallelized since the operations are commutative/associative. 回答2: The

“Approximate” greatest common divisor

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问题 Suppose you have a list of floating point numbers that are approximately multiples of a common quantity, for example 2.468, 3.700, 6.1699 which are approximately all multiples of 1.234. How would you characterize this "approximate gcd", and how would you proceed to compute or estimate it? Strictly related to my answer to this question. 回答1: You can run Euclid's gcd algorithm with anything smaller then 0.01 (or a small number of your choice) being a pseudo 0. With your numbers: 3.700 = 1 * 2

JS how to find the greatest common divisor [closed]

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问题 I would like to find the greatest common divisor using JavaScript. Anyone done that before and willing to share? 回答1: Here is a recursive solution. var gcd = function(a, b) { if (!b) { return a; } return gcd(b, a % b); } Our base case is when b is equal to 0 . In this case, we return a . When we're recursing, we swap the input arguments but we pass the remainder of a / b as the second argument. 回答2: Taken from Wikipedia. Recursive: function gcd_rec(a, b) { if (b) { return gcd_rec(b, a % b); }

what is the fastest way to find the gcd of n numbers?

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what is the fastest way to compute the greatest common divisor of n numbers? akjlab You should use Lehmer's GCD algorithm . Without recursion: int result = numbers[0]; for(int i = 1; i < numbers.length; i++){ result = gcd(result, numbers[i]); } return result; For very large arrays, it might be faster to use the fork-join pattern, where you split your array and calculate gcds in parallel. Here is some pseudocode: int calculateGCD(int[] numbers){ if(numbers.length <= 2){ return gcd(numbers); } else { INVOKE-IN-PARALLEL { left = calculateGCD(extractLeftHalf(numbers)); right = calculateGCD

Java: get greatest common divisor

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问题 I have seen that such a function exists for BigInteger , i.e. BigInteger#gcd. Are there other functions in Java which also work for other types ( int , long or Integer )? It seems this would make sense as java.lang.Math.gcd (with all kinds of overloads) but it is not there. Is it somewhere else? (Don't confuse this question with "how do I implement this myself", please!) 回答1: For int and long, as primitives, not really. For Integer, it is possible someone wrote one. Given that BigInteger is a

Finding the GCD without looping - R

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问题 So I'm trying to learn R and using a number of resources including a book called "Discovering Statistics using R" and a bunch of other cool eBooks. I understand a great method in programming is the Euclid's Algorithm. Implementing it in a loop can be achieved like this: gcd(x,y) //assuming x is the largest value //do r = x%y; x = y; y = r; //while r != 0; return x; After several searches on Google, SO and Youtube refreshing my memory of gcd algorithms, I wasn't able to find one that doesn't

How does the Euclidean Algorithm work?

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问题 I just found this algorithm to compute the greatest common divisor in my lecture notes: public static int gcd( int a, int b ) { while (b != 0) { final int r = a % b; a = b; b = r; } return a; } So r is the remainder when dividing b into a (get the mod). Then b is assigned to a , and the remainder is assigned to b , and a is returned. I can't for the life of my see how this works! And then, apparently this algorithm doesn't work for all cases, and this one must then be used: public static int

How to find GCD, LCM on a set of numbers

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What would be the easiest way to calculate Greatest Common Divisor and Least Common Multiple on a set of numbers? What math functions can be used to find this information? Jeffrey Hantin I've used Euclid's algorithm to find the greatest common divisor of two numbers; it can be iterated to obtain the GCD of a larger set of numbers. private static long gcd(long a, long b) { while (b > 0) { long temp = b; b = a % b; // % is remainder a = temp; } return a; } private static long gcd(long[] input) { long result = input[0]; for(int i = 1; i < input.length; i++) result = gcd(result, input[i]); return