Why is the output NaN?-CodePudding

I'm learning Javascript, when I want to calculate using a formula the resulting data is NaN.

I want the resulting data to be

ar = [37, 36.63, 35.68, 38.81, 37.67, 37.64, 37.64, 39.74, 40.67, 40.61];

ma = [0.00, 0.63, 3.32, 0.81, 0.33, 0.36, 2.36, 1.26, 0.33, 1.61];

Is there something wrong with my code that is making me get this answer?

var suhu = [37, 36, 39, 38, 38, 38, 40, 41, 41, 39];

var ar = []
var ma = []
var temp = 0

// AR
for (var i = 1; i < suhu.length; i  ) {
  ar[0] = suhu[0]
  temp = 0.99 * suhu[i - 1]   0.06 * ma[i - 1]
  ar.push(temp)
}

// MA
for (var j = 0; j < suhu.length; j  ) {
  suhu[j] = Math.abs(suhu[j] - ar[j]);
  ma.push(suhu[j])
}

console.log(ar);
// 37, NaN, NaN, NaN, NaN, NaN, NaN, NaN, NaN, NaN
console.log(ma);
// 0, NaN, NaN, NaN, NaN, NaN, NaN, NaN, NaN, NaN

CodePudding user response：

The problem is that the calculation of ar[i] depends on ma[i-1] and ma[i] depends on ar[i] so you need to calculate these in the right order in a single loop.

const suhu = [37, 36, 39, 38, 38, 38, 40, 41, 41, 39];
const ar = [];
const ma = [];

// Calucate AR and MA together
ar[0] = suhu[0]
for (var i = 0; i < suhu.length; i  ) {

  if (i > 0)
    ar.push(0.99 * suhu[i - 1]   0.06 * ma[i - 1])

  ma.push(Math.abs(suhu[i] - ar[i]));
}

console.log(ar);
// [37, 36.63, 35.6778, 38.809332, 37.66855992, 37.639886404799995,
//  37.641606815711995, 39.74150359105728, 40.66550978453656, 40.6100694129278]
console.log(ma);
// [0, 0.6300000000000026, 3.3222000000000023, 0.8093319999999977, 0.33144008000000014,
//  0.36011359520000497, 2.358393184288005, 1.2584964089427189, 0.3344902154634397, 1.6100694129277997]

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The results are accurate to more than 2 decimal places and you will need that to calculate the next values correctly. You can change the precision once all the values have been calculated though.

CodePudding user response：

So what should I do about it?

Calculating the values in ar and ma seems so dependent on each other. To calculate ar[i] you need ma[i-1] and for ma[i] you need ar[i]. This should be a single loop. You can't first compute one array and then the other.

var suhu = [37, 36, 39, 38, 38, 38, 40, 41, 41, 39];
var ar = [suhu[0]];
var ma = [0];

for (let i = 1; i < suhu.length;   i) {
  ar[i] = 0.99 * suhu[i - 1]   0.06 * ma[i - 1];
  ma[i] = Math.abs(suhu[i] - ar[i]);
}

console.log(ar);
console.log(ma);

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CodePudding user response：

you havent initialized the ma[] at start and used it for initializing ar[] so it producing Nan value.

CodePudding user response：

In JavaScript, NaN stands for Not a Number. It represents a value which is not a valid number. It can be used to check whether a number entered is a valid number or not a number.

From https://www.geeksforgeeks.org/javascript-number-nan-property/#:~:text=In JavaScript, NaN stands for,number or not a number.