On 13/07/2019 22:36, Oscar Benjamin wrote:
Generally it is a lot easier to understand SymPy if you are
experienced with Python. A lot of our users are new to both Python and
SymPy and I think that makes it hard to explain what's going on. Some
things would be cleaner for users if SymPy was not embedded within
Python and can be confusing unless you already know Python well and
can see why things are the way they are.
--
Oscar
I am also fairly new to Python and sympy, but I think I have pushed
through this pain barrier.
As far as I can see, you really need to use symbols() or var() to set up
variables which are going to be used as symbols in bits of algebra or
calculus, but you do not need to make a variable symbolic if it is just
going to be used to hold expressions or for some other pythonic purpose,
such as a counter. However, no harm is done (someone correct me if I am
wrong) if you create a lot of symbols, which you can do with :
from sympy.abc import *
because if, say, you subsequently assign X=42 that will harmlessly
destroy the sympy symbol attached to x which will become pythonic again,
but you obviously want to use it as a constant so that is fine.
I think a good strategy is to either save some letters for use as
pythonic variables, or only use variables with more than one character
as pythonic variables (they don't look nice in expressions, anyway)
If you want to use x in expressions, then it is probably best not to
assign it to 42 (as above) but to leave it symbolic, and use subs to
replace it in an expression by 42.
David
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