Update README.md #1
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Update required version of Python
GSam
added a commit
that referenced
this pull request
Aug 23, 2021
This is useful for more general, albeit sometimes inefficient, summation
code. Just copying some taylor expansion code from the internet worked
with sympy but not symengine due to the following error:
Traceback (most recent call last):
File "example.py", line 32, in <module>
taylor(symengine.sympify('1/(1-x-x^2)'), 0, 15)
File "example.py", line 27, in taylor
p = p + (function.diff(x, i).subs(x, x0))/(factorial(i))*(x - x0)**i
File "symengine_wrapper.pyx", line 923, in symengine.lib.symengine_wrapper.Basic.diff
File "symengine_wrapper.pyx", line 4020, in symengine.lib.symengine_wrapper.diff
OverflowError: can't convert negative value to size_t
There are a number of inconsistencies compared to the regular sympy library:
1. Takes no argument:
>>> symengine.sympify('x**2').diff()
2*x
This actually seems helpful, except when you have symengine#2 misleading you.
This is not accepted in sympy, but doesn't necessarily need a fix.
2. Takes a standalone integer argument and returns a nonsense answer:
>>> symengine.sympify('x**2').diff(1)
x**2
This is simply not accepted in the regular sympy library.
3. Takes multiple integer arguments and aggregates:
diff(x, 1, 1) == diff(x, 2)
This does not occur with the sympy library, and does not seem useful.
It can easily be replaced with diff(x, x), if repetition was necessary.
4. Takes only integer arguments > 1:
diff(x, 0) returns integer overflow
This is accepted in sympy.
In this patch, 2-4 are all fixed. #1 seems like a potentially useful (and
likely used) feature.
Signed-off-by: Garming Sam <garming@catalyst.net.nz>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Update required version of Python