Joanna - 1 year ago 205
Javascript Question

# Calculating Pi in JavaScript using Gregory-Leibniz Series

I have to calculate value of Pi using Gregory-Leibniz series:

``````pi = 4 * ((1/1 - 1/3) + (1/5 - 1/7) + (1/9 - 1/11) + ...)
``````

I want to write a function in JavaScript that would take number of digits that needs to be displayed as an argument. But I'm not sure if my way of thinking is fine here, I have just started learning JS.

This is what I got so far:

``````function pi(n) {
var pi = 0;
for (i=1; i <= n; i+2) {
pi = 4 * ((1/i) + (1/(i+2)))
}
return pi;
}
``````

How do I write pi calculation so it calculates values till
`n`
?

You could use an increment of 4 and multiply at the end of the function with `4`.

`n` is not the number of digits, but the counter of the value of the series.

``````function pi(n) {
var v = 0;
for (i = 1; i <= n; i += 4) {  // increment by 4
v +=  1 / i - 1 / (i + 2); // add the value of the series
}
return 4 * v;                  // apply the factor at last
}

console.log(pi(1000000000));``````

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