Sympy will not solve vector equations and the vector module seems to be
an after thought. Convert the vector equations to systems of non-linear
scalar equations and hold your breath for the solver to give and answer -
https://docs.sympy.org/latest/modules/solvers/solvers.html
Part of the problem is that sympy is not a rule based computer algebra
system. Everything is hardcoded
On 10/30/21 9:33 AM, Andreas Schuldei wrote:
Obviously you looked at the code. Thank you! So you didn't see any
obvious type screwups, either? Do you have other tips or remarks?
[email protected] schrieb am Samstag, 30. Oktober 2021 um 14:23:41 UTC+2:
I do not know solve well but I suspect that it cannot handle
vector equations. There should probably be separate equations for
the components.
Kalevi Suominen
On Saturday, October 30, 2021 at 9:28:06 AM UTC+3 Andreas Schuldei
wrote:
I have a system of longish equations and when calling .solve()
on it, I get this traceback:
Traceback (most recent call last):
File "C:/Users/Andreas
Schuldei/PycharmProjects/lissajous-achse/hgü-kabel-detektion-symbolic.py",
line 109, in <module>
result = solve(equations, (CM0, theta_i, theta_j, theta_k,
i, a, B_earth))
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\solvers\solvers.py",
line 1096, in solve
solution = _solve_system(f, symbols, **flags)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\solvers\solvers.py",
line 1730, in _solve_system
i, d = _invert(g, *symbols)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\solvers\solvers.py",
line 3118, in _invert
rhs -= indep
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\numbers.py",
line 2194, in __sub__
return Rational.__sub__(self, other)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py",
line 89, in __sympifyit_wrapper
return func(a, b)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\numbers.py",
line 1725, in __sub__
return Number.__sub__(self, other)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py",
line 89, in __sympifyit_wrapper
return func(a, b)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\numbers.py",
line 733, in __sub__
return AtomicExpr.__sub__(self, other)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py",
line 251, in _func
return func(self, other)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py",
line 126, in binary_op_wrapper
return f(self)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py",
line 127, in binary_op_wrapper
return func(self, other)
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\vector\basisdependent.py",
line 352, in __rsub__
raise TypeError("Invalid argument types for subtraction")
TypeError: Invalid argument types for subtraction
Process finished with exit code 1
I stared at my code long and hard, and fixed all instances of
wrong types that i could think of. Also, in order to catch the
error earlier, I tried insterting .simplify() calls in places
that might benefit from them - but the process ran for hours,
doing the simplyfy() without even reaching the solve() call.
So I am asking for tricks to investigate the types and them
fitting together, earlier. You can find my code attached.
(please critique it, I want to learn!).
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