Mensanator wrote:
On May 22, 11:32 am, "Dutton, Sam" <[EMAIL PROTECTED]> wrote:
I've noticed that the value of math.pi -- just entering it at the interactive
prompt -- is returned as 3.1415926535897931, whereas (as every pi-obsessive
knows) the value is 3.1415926535897932... (Note the 2 at the end.)
Is this a precision issue, or from the underlying C, or something else? How is
math.pi calculated?
If you actually need that many digits, use a different library.
import gmpy
print gmpy.pi(64) # 64 bit precision
3.14159265358979323846
print gmpy.pi(128) # 128 bit precision
3.141592653589793238462643383279502884197
print gmpy.pi(16384) # 16384 bit precision
3.14159265358979323846264338327950288419716939937510582097494459
23....
Heh!
I wonder who needs that many digits?
Certainly not number theorists (they need a LOT more). Certainly not
physicists -- they need about 30 digits to be within 1% of any
measurement from molecules to galaxies. Certainly not engineers, they
need half the digits that physicists need. Cryptographers are making a
dire mistake if they are using PI in any computations (possible
exception for elliptic curves -- see number theorists, above) ... so --
other than PI-philes, who needs PI to thousands of digits?
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