Hi Oscar,
It wouldn't be hard to make any new definition of a Symbol with the
same name as a previously created symbol raise an error but it would
break the assumption that it is okay to define a symbol that is only
used local to some context and that assumption is depended on by many
users and
Hi David,
However, my feeling is that some proportion of SymPy users will work
interactively - in one scope - without defining any Python functions. So
they might calculate a polynomial without regard to any assumptions, and
then wish to apply an assumption for one specific calculation and
Hi David,
Thanks for picking this up. I wanted to comment that in your example,
the two symbols are defined differently:
Symbol("x", positive=True)
Symbol("x")
that is to say, with different assumptions. For the issue that I was
reporting, the two symbols that were defined with identical
Dear Sympy developers,
This is not a serious issue, but I wanted to flag it. According to the
documentation (and IMO correctly):
acos(x) = asec(1/x)
So I was surprised to see the contrast between:
>>> acos(Rational(1,2))
pi/3
>>> asec(Rational(2,1))
asec(2)
I would expect the previous
15:55, Oscar Benjamin wrote:
On Wed, 7 Apr 2021 at 14:43, 'Bruce Allen' via sympy
wrote:
David, Oscar,
Thank you for your help.
Oscar, the list 'u' was created in the course of a calculation, and
saved as a .pkl file. I then reloaded it and want to manipulate the
saved equations, of which u[7
David, Oscar,
Thank you for your help.
Oscar, the list 'u' was created in the course of a calculation, and
saved as a .pkl file. I then reloaded it and want to manipulate the
saved equations, of which u[7] is an example. I found an even cleaner
example, see below.
I have the impression
I have a very basic sympy question, which has me stumped, and am hoping
that someone here can set me straight. I have an expression for which
subs() seems to have no effect:
>>> a=Symbol('a', real=True, positive=True)
>>> q=u[7]
>>> q
-a*(45*a**18 - 120*a**16 + 240*a**12 - 504*a**8 +
[NOTE: I mistakenly sent several replies to individuals rather than to
the group. Several are moot, but I did not want to leave them off-list.
So I am resending below. Sorry about that! Bruce]
Dear Aaron,
Thank you again for your help. I found the solution to my problem
(which involves
[NOTE: I mistakenly sent several replies to individuals rather than to
the group. Several are moot, but I did not want to leave them off-list.
So I am resending below. Sorry about that! Bruce]
Dear Chris,
THANK YOU! That's an excellent solution for me. I did not know about
it and
[NOTE: I mistakenly sent several replies to individuals rather than to
the group. Several are moot, but I did not want to leave them off-list.
So I am resending below. Sorry about that! Bruce]
Hi Oscar,
Thanks for the quick reply.
The symbol 'a' is declared to be real and positive. But
[NOTE: I mistakenly sent several replies to individuals rather than to
the group. Several are moot, but I did not want to leave them off-list.
So I am resending below. Sorry about that! Bruce]
Hi Oscar,
Thanks for your comments.
def MyAbs(x):
x1=symbols('x1',real=True,positive=True)
Dear Chris,
On 31.03.21 05:48, Chris Smith wrote:
Oscar posted code at issue https://github.com/sympy/sympy/issues/19164
for a interva-based Newton solver.
Thank you, that's very useful. I didn't know about interval arithmetic.
I just implemented the following, which works very well and
Hi Aaron,
This section of the tutorial may help to clear things up
https://docs.sympy.org/latest/tutorial/gotchas.html. This blog post
also goes into more detail about how variables work in Python
https://nedbatchelder.com/text/names.html.
Thanks for the pointers. I'll study them.
What I
Hi Aaron,
Thanks for your help!
def MyAbs(x):
x1=symbols('x1',real=True,positive=True)
x1 = x.evalf(subs={a:0.573})
if x1 < 0.0:
return S(-1)*x
else:
return x
- Defining x1 as a symbol does nothing in this code, as you
immediately overwrite it with
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