# The given ? value in docs

In Acos (docs), the example shows a ? value that ends with a 0:

Const Pi = 3.14159265358979323846264338327950

according to wikipedia, ? is not a finite value (? is an irrational number)
http://en.wikipedia.org/wiki/Pi

So, the Const definition in Acos is false ?

I think the constant will be accurate for most scenarios. Even 5 decimal places (3.14159) should suffice for most problems.

Not sure how one would otherwise represent an infinite value (e.g. Pi) on a finite binary machine?

Having a ‘0’ somewhere does not means it is a ‘finite’ value.

Wikipedia gives the first 100 decimal digits of Pi which contains several ‘0’:
3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679

The Const value appears correct to me, truncated/rounded at this particular ‘0’.

Cheers,
Guy.

Guy: I opened that wikipedia page, (and the same in French), but I do not read to that location (100 digits ?).

It is here:
http://en.wikipedia.org/wiki/Pi

In the section “Approximate Value”.

Cheers,
Guy.

Guy: thanks.

Alwyn: sorry for the mispelling. This happens to me some days here and there to mis-place my fingers on the keyboard.
I even have a bad period of time where my right hand fingers always type the next keycap: very tedious!

a double can anyway just hold around 15 digits of precision. So the last digits of our const are not stored…

Christian: thank you for the laugh !

;-

Das, ist es vom Volksgesunden Menschenverstand!

For precision references, you only need 39 digits of pi to calculate the circumference of the observable universe to within a hydrogen atom…