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Thread: Gmpy2 Newbie Working on Precision
Post: RE: Gmpy2 Newbie Working on Precision
(Jan-22-2024, 03:44 AM)charlesrkiss Wrote: I went to a random calculator website: https://math.tools/calculator/trignometry/asin
From there I found similar results and created a table of the valu... |
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casevh |
General Coding Help |
5 |
487 |
Jan-23-2024, 06:51 AM |
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Thread: Precision with Decimal Type
Post: RE: Precision with Decimal Type
(Jan-17-2024, 10:45 PM)charlesrkiss Wrote: Hello Perfringo,
You can see in the second balloon above (repeated below) how theta is close to a ninety-digit number that I input to math.cos, but my int... |
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casevh |
General Coding Help |
9 |
634 |
Jan-18-2024, 05:55 AM |
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Thread: Looking for clarification related to performance
Post: RE: Looking for clarification related to performan...
It is difficult to provide a complete answer without understanding the context - both of the person making the statement "function calls are slow" and what your program does. So let's look at adding t... |
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casevh |
General Coding Help |
5 |
1,996 |
Apr-03-2022, 03:53 AM |
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Thread: numpy.dot() result different with classic computation for large-size arrays
Post: RE: numpy.dot() result different with classic comp...
The quick answer is that numpy.dot calculates the using the type in the construction of arrary.array. "q" represents a 64-bit signed integer which overflows at 2**63-1. This eventually overflows and t... |
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casevh |
General Coding Help |
5 |
1,829 |
Jan-25-2022, 08:09 AM |
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Thread: efficiency of CPython expression comppilation
Post: RE: efficiency of CPython expression comppilation
Python does perform constant expression optimizations. The dis (short for disassemble) module can show it in action.
>>> def f(x):
... return x/(7*24*60*60)
...
>>> import dis
&g... |
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casevh |
News and Discussions |
1 |
1,249 |
Jan-09-2022, 06:03 AM |
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Thread: f-strings round float down too much
Post: RE: f-strings round float down too much
You are correct. My memory is a bit hazy.
Looking at this again, I'm not exactly sure what is the bug.... |
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casevh |
News and Discussions |
5 |
2,515 |
Dec-29-2021, 04:13 PM |
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Thread: f-strings round float down too much
Post: RE: f-strings round float down too much
There are at least two different strategies for representing 64-bit IEEE floating point values as a decimal string that round-trip. In other words, they guarantee that x == float(str(x)). One choice i... |
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casevh |
News and Discussions |
5 |
2,515 |
Dec-29-2021, 07:25 AM |
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Thread: unexpected decimal.InvalidOperation
Post: RE: unexpected decimal.InvalidOperation
The behavior you are seeing is part of IEEE-754 standard. The easiest chart I found is in the "Special Operations" section of https://steve.hollasch.net/cgindex/codin...float.html.
The specification... |
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casevh |
News and Discussions |
2 |
1,845 |
Dec-25-2021, 07:53 AM |
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Thread: smallest float that can increment a given value
Post: RE: smallest float that can increment a given valu...
(Dec-11-2021, 06:35 PM)snippsat Wrote: (Dec-11-2021, 06:05 PM)Skaperen Wrote: what would you pick for a name?There is hint in his post,as he already has chosen names in gmpy2.
Also hi is the autho... |
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casevh |
News and Discussions |
7 |
2,770 |
Dec-11-2021, 10:22 PM |
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Thread: smallest float that can increment a given value
Post: RE: smallest float that can increment a given valu...
sudo apt install libmpc-devThat will install the GMP, MPFR, and MPC libraries. You can then compile from source.
Or if you are using a version of Python distributed by Ubuntu, you can use
sudo apt i... |
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casevh |
News and Discussions |
7 |
2,770 |
Dec-11-2021, 10:08 PM |
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Thread: smallest float that can increment a given value
Post: RE: smallest float that can increment a given valu...
Not exactly, but the math module provides the function nextafter(x,y) that returns the next floating-point value after x towards y.
>>> math.nextafter(12,0) # The next float towards 0.
11.99... |
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casevh |
News and Discussions |
7 |
2,770 |
Dec-11-2021, 05:32 AM |
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Thread: shouldn't this raise an exception?
Post: RE: shouldn't this raise an exception?
>>> from decimal import *
>>> getcontext()
Context(prec=28, rounding=ROUND_HALF_EVEN, Emin=-999999, Emax=999999, capitals=1, clamp=0, flags=[], traps=[InvalidOperation, DivisionByZer... |
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casevh |
News and Discussions |
3 |
2,752 |
Dec-08-2021, 05:01 AM |
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Thread: who is Barry?
Post: RE: who is Barry?
Barry was one of the early users of Python and he is still involved with Python.
You might want to look at PEP 0401 ( https://www.python.org/dev/peps/pep-0401/ ). |
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casevh |
Bar |
7 |
2,599 |
Nov-15-2021, 11:01 PM |
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Thread: Calculate the Euler Number with more decimal places
Post: RE: Calculate the Euler Number with more decimal p...
(Oct-22-2021, 12:17 AM)Pedroski55 Wrote: Thanks for your replies!
I use Ubuntu 20.04
I only tried to install gmpy2 using pip.
I'm not very clear about installing from source, I never do that, but... |
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casevh |
General Coding Help |
10 |
4,392 |
Oct-31-2021, 03:46 AM |
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Thread: Pass by object reference when does it behave like pass by value or reference?
Post: RE: Pass by object reference when does it behave l...
The Python interpreter only comprehends pass by object reference. Whether a new object is returned (kind of, but not really, like pass by value) or an existing object is modified (kind of, but not rea... |
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casevh |
General Coding Help |
2 |
2,513 |
Sep-07-2020, 06:05 AM |
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Thread: system-wide unique incrementing string or number
Post: RE: system-wide unique incrementing string or numb...
I would look at time.monotonic() and some related functions. They are designed to monotonically increase even if NTP is used to adjust the time. I don't know how they behave after a system reboot if t... |
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casevh |
News and Discussions |
11 |
4,010 |
Jul-07-2020, 07:05 PM |
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Thread: time complexity of int
Post: RE: time complexity of int
Python does use an improved algorithm for squaring large numbers. The improvement just decreases the constant so the time complexity doesn't change. The improvement is measurable.
a is 1232 bits long... |
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casevh |
News and Discussions |
6 |
2,625 |
Jul-05-2020, 03:03 PM |
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Thread: time complexity of int
Post: RE: time complexity of int
Yes, comparison is also O(n). |
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casevh |
News and Discussions |
6 |
2,625 |
Jul-05-2020, 05:06 AM |
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Thread: time complexity of int
Post: RE: time complexity of int
Assume n is length of the number in bits and let's use ^ for exponentiation.
Addition and subtraction are O(n).
Multiplication uses the Karatsuba algorithm that is O(n^1.585) instead of the classica... |
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casevh |
News and Discussions |
6 |
2,625 |
Jul-04-2020, 08:28 PM |
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Thread: PyArray_SimpleNew gives "ValueError: array is too big; for 3-cubed array
Post: RE: PyArray_SimpleNew gives "ValueError: array is ...
Have you tried declaring dims[] as "npy_intp dims[3];"?
casevh |
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casevh |
General Coding Help |
1 |
3,023 |
Nov-30-2019, 05:02 AM |