How do I make this function more precise?

user_15149723 0
Viewed 69

I'm a beginner and I made a function to calculate the length of a semi-circular infinite snake figure. I took in two arguments; one of the radius the initial circle, and the next to be the precision (which is just the number of semi-circles).

Here's a diagram of the snake I'm talking about.

Here's what I wrote:

function snake(radius, precision) {
    var pi = 3.14159265359
    var exp = 1 - precision; 
    var sub = Math.pow(2, exp);
    var product = 2 - sub;
    var length = pi * radius * product
        return length
}

I'm noticing that at one point the precision doesn't matter when I go really high as the value it return is the same. Is there a way to make it more precise?

javascript
3 Answers

You may use the constant Math.PI instead of your pi variable.

user_102084740

Feels like Number.toPrecision() is what you are looking for. Below is slightly cleaned up version of your code snippet. For the return value I'm using length.toPrecision(50):

function snake(radius, precision) {
    const exp = 1 - precision; 
    const sub = Math.pow(2, exp);
    const product = 2 - sub;
    const length = Math.PI * radius * product;
    return length.toPrecision(50);
}

console.log(snake(5, 55));

Yo can find out more about toPrecision() here. The max precision value is 100.

user_149021870

This will be my method,

Length can be get by sum of the below series according to the screen shot,

PI X R (1 + 1/2 + 1/4 + ...)

S(n) = PIxR(1-0.5^n)/(1-0.5)

So the JavaScript function is,

function length(r, n) {
 const ln = Math.PI * r * (1 - Math.pow(0.5, n))/(1 - 0.5);
 return ln.toPrecision(50);
}
user_113060280
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