Troubleshooting NaN Output in Javascript Array Factorial Calculation

Question

Troubleshooting NaN Output in Javascript Array Factorial Calculation

var elements = [5,4,3,2,1];

document.write("<br>Factorial: " + calculateFactorial(elements));

//factorial function Ex. 5! = 5*4*3*2*1 = 120

function calculateFactorial(values){
        var result = [];
        for (i = 0; i < values.length; ++i){
            var factorialValue = 1;
            for (j = 1; j <= values[i]; j++){
                factorialValue = factorialValue * j;
            }
            result.push(factorialValue);
        }
        return result.join(",");
    }

I have developed a program that takes an array of random numbers as input from the user and then calculates different metrics based on those numbers.

The current focus is to compute the factorial of each individual number in the array and present them in sequence.

However, the current implementation is resulting in NaN being displayed instead of the desired output.

What errors do you think might be causing this issue? Is there something crucial missing from my code?

CURRENT OUTPUT

Factorial: NaN

EXPECTED OUTPUT

Factorial: 120,24,6,2,1

javascript arrays nested-loops nan factorial

Answer 1

Answer №1

Here are some incorrect (or at least peculiar) aspects in your code:

The variable f is assigned a number value, but it appears you expect your function to return an array.
The condition i <= params.length should actually be i < params.length. Remember that array indices start from 0 and go up to length-1.
You are multiplying the accumulator variable by params[j], where j is any number less than the current array item being examined. This leads to a result of NaN because when i == 0, the loop continues until j == 5, yet params[5] is undefined, resulting in NaN.

It looks like what you want can be achieved through this code:

function factorial(n) {
    // Compute the factorial of the number n!
    var acc = 1;
    while (n > 0) acc *= n--;
    return acc;
}
function facArray(params) {
    var f = [];
    for (var i=0; i<params.length; i++)
        f[i] = factorial(params[i]);
    return f;
}

Answer 2

Here are some incorrect (or at least peculiar) aspects in your code:

The variable f is assigned a number value, but it appears you expect your function to return an array.
The condition i <= params.length should actually be i < params.length. Remember that array indices start from 0 and go up to length-1.
You are multiplying the accumulator variable by params[j], where j is any number less than the current array item being examined. This leads to a result of NaN because when i == 0, the loop continues until j == 5, yet params[5] is undefined, resulting in NaN.

It looks like what you want can be achieved through this code:

function factorial(n) {
    // Compute the factorial of the number n!
    var acc = 1;
    while (n > 0) acc *= n--;
    return acc;
}
function facArray(params) {
    var f = [];
    for (var i=0; i<params.length; i++)
        f[i] = factorial(params[i]);
    return f;
}

Answer 3

Answer №2

If you're looking for a solution, you might consider using the `fact` function provided in Felix Kling's response here. This implementation utilizes both `Array.map` and `Array.join` to calculate the factorial of a number.

function fact(x) {
   if (x == 0) return 1;
   return x * fact(x - 1);
}
function factorial(arr) {
   var result = arr.map(fact);
   return result.join(",");
}

Answer 4

If you're looking for a solution, you might consider using the `fact` function provided in Felix Kling's response here. This implementation utilizes both `Array.map` and `Array.join` to calculate the factorial of a number.

function fact(x) {
   if (x == 0) return 1;
   return x * fact(x - 1);
}
function factorial(arr) {
   var result = arr.map(fact);
   return result.join(",");
}

Answer 5

Answer №3

give this code a shot

let numList = [7, 6, 5, 4, 3];

document.write("<br>Factorial: " + calculateFactorial(numList).join(','));

function calculateFactorial(input){
        let outputArray = [];
        for (index = input.length - 1; index >= 0 ; index--){
            let factorialValue = 1;
            for (innerIndex = 0; innerIndex < index; innerIndex++){
                factorialValue = factorialValue * input[innerIndex];
            }
             outputArray.push(factorialValue);
        }
       return outputArray;
    }

Answer 6

give this code a shot

let numList = [7, 6, 5, 4, 3];

document.write("<br>Factorial: " + calculateFactorial(numList).join(','));

function calculateFactorial(input){
        let outputArray = [];
        for (index = input.length - 1; index >= 0 ; index--){
            let factorialValue = 1;
            for (innerIndex = 0; innerIndex < index; innerIndex++){
                factorialValue = factorialValue * input[innerIndex];
            }
             outputArray.push(factorialValue);
        }
       return outputArray;
    }

Answer 7

Answer №4

Everything happens within a while loop :)

var numbers = [9,8,7,6,5];
var length = numbers.length-1;
while(length--) {
    numbers[length] *= numbers[length+1];
}

numbers;// [5040,336,42,12,5]

Simply multiplying each element starting from the end.

Answer 8

Everything happens within a while loop :)

var numbers = [9,8,7,6,5];
var length = numbers.length-1;
while(length--) {
    numbers[length] *= numbers[length+1];
}

numbers;// [5040,336,42,12,5]

Simply multiplying each element starting from the end.

Troubleshooting NaN Output in Javascript Array Factorial Calculation

Answer №1

Answer №2

Answer №3

Answer №4

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