David,
I'm not sure I understand what algebraic manipulations you are referring
to. In the example, the algebraic manipulation is done with sympy
variables. Only the final expressions are evaluated with floating point
numbers substituted in. The substitutions of floating point numbers do have
to
On 23/10/2020 11:59, Oscar Benjamin wrote:
Hi Jason,
I'm approaching this from the perspective that this is a bug in
cse/lambdify and that you want to identify which part of a large
expression tree triggers the bug. Since evaluating the whole
expression is slow I would start by testing smaller
Also, if anyone is curious what prompted this question, I do now have a
nice example running in the pydy docs for this problem:
https://pydy.readthedocs.io/en/latest/examples/carvallo-whipple.html
There are still some things that are incorrect in the derivation (the
warning boxes) but the
Oscar,
Yes, this is what I want to check. Thanks for taking the time to write this
code. I'll give it a try.
In the meantime I did get my code to run. I think Python was actually being
"Killed" by trying to lambdify an expression with thousands of operations.
I then switched to expr.evalf(subs=)
Hi Jason,
I'm approaching this from the perspective that this is a bug in
cse/lambdify and that you want to identify which part of a large
expression tree triggers the bug. Since evaluating the whole
expression is slow I would start by testing smaller subexpressions and
work up from there. You
Oscar,
Yes I can try evaluating in different orders. That's an interesting idea.
I also may be breaking lambdify with too many arguments. I can store the
numerical results of each subexpression in a dictionary, then identify the
minimal set of variables in each subsequent subexpression, and only
Yes, you are right that the email is about a different topic. However, it
can be worth noting that evaluating floating-point expressions in different
order, which is basically what you do using cse:s, can give different
results due to the floating-point quantization/rounding happening at
different
