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CS 3723
Programming Languages |
13. Multi-Precision Float
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13.1. Multi-Precision Float:
Python lets ints be arbitrarily large (subject to available memory).
Ordinary Python can't handle floating point numbers with more significant
digits than a double (about 16), so some other software is
required:
- mpmath:
a third-party addition to Python, this seems the best choice.
I installed it on my Linux system (using Python 2.6.5) at home
with no trouble. It is available
for Python 2.5 or higher, including Python 3.x. My install required
root privileges, so I cannot install it on an elk, but I'll see if
the systems people will do that. Besides Linux, it should also install
easily on an apple, but I haven't tried that. Also
available for windows.
It is pure-Python code, and seems very sophisticated, with
a lot of fancy capabilities and features. I'm just getting started
on this (see below). See also mpmath documentation.
Here are a few computations:
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mpmath: Sample Calculations |
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# mpmath_test.py
from mpmath import *
import sys
mp.dps = 50 # 50 digit calculations
print "Precision: ", mp.dps
print mpf(2) ** mpf('0.5') # sqrt(2)
print 2*pi # 2*pi
near_int = e ** (pi * mpf(163) ** mpf('0.5'))
print near_int # very close to an int
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% Python mpmath.py
Precision: 50
1.4142135623730950488016887242096980785696718753769
6.2831853071795864769252867665590057683943387987502
262537412640768743.99999999999925007259719818568887
(all digits above are correct)
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- Others:
Python has other such libraries, as do C and Lisp and many others.
(Revision date: 2014-07-04.
Please use ISO 8601,
the International Standard.)
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