CODEWITHSUNDEEP
pythonmathsympyequation-solving
Suyoung Park
Suyoung Park

Reputation: 31

how to solve trigonometric equations on python

I am trying to solve 3 of trigonometric equations in python. I used Sympy library but I got a error such as 'TypeError: can't convert expression to float'

Here is My Python Source code:

from sympy import Symbol, solve, Eq
from math import*

# Robot Arm length
L1 = 0
L2 = 97.9
L3 = 120
L4 = 120
L5 = 184

# location
x = L1+L2+L3+L4+L5
y = 0
z = 0

x1 = Symbol('x1',real = True)
x2 = Symbol('x2',real = True)
x3 = Symbol('x3',real = True)

#trigonometric equations

e1= Eq(L1 - (5*sin(x1))/2 - L4*(cos(x1)*sin(x2)*sin(x3) - cos(x1)*cos(x2)*cos(x3)) - L5*(cos(x4)*(cos(x1)*sin(x2)*sin(x3) - cos(x1)*cos(x2)*cos(x3)) + sin(x4)*(cos(x1)*cos(x2)*sin(x3) + cos(x1)*cos(x3)*sin(x2))) + L2*cos(x1) + L3*cos(x1)*cos(x2) - x)
e2= Eq((5*cos(x1))/2 + L4*(cos(x2)*cos(x3)*sin(x1) - sin(x1)*sin(x2)*sin(x3)) + L5*(cos(x4)*(cos(x2)*cos(x3)*sin(x1) - sin(x1)*sin(x2)*sin(x3)) - sin(x4)*(cos(x2)*sin(x1)*sin(x3) + cos(x3)*sin(x1)*sin(x2))) + L2*sin(x1) + L3*cos(x2)*sin(x1) - y)
e3= Eq(-L4*(cos(x2)*sin(x3) + cos(x3)*sin(x2)) - L3*sin(x2) - L5*(cos(x4)*(cos(x2)*sin(x3) + cos(x3)*sin(x2)) + sin(x4)*(cos(x2)*cos(x3) - sin(x2)*sin(x3))) - z)

solve([e,e2,e3],x1,x2,x3)

x1 = degrees(x1)
x2 = degrees(x2)
x3 = degrees(x3)

print("degree values : ",x1,x2,x3)

I added My error message:

enter image description here

Can anyone tell me which part should I change in my code?

Upvotes: 3

Views: 12052

Answers (3)

Alex Goldenberg
Alex Goldenberg

Reputation: 11

In this line from the source code in the original question, I believe the typo e should be re-written e1

solve([e,e2,e3],x1,x2,x3)

Upvotes: 1

user6655984
user6655984

Reputation:

from math import * is the major error here. The functions math.sin and math.cos are for numeric computation only, you can't give them symbolic arguments. Any mathematical functions must be imported from SymPy in order to use them in symbolic computations.

Guideline: when using SymPy, don't import anything from math. Changing the import to

from sympy import *

will solve most of the issue. You'll still have to define x4 that's currently undefined.

Upvotes: 7

Patrick Maynard
Patrick Maynard

Reputation: 314

I couldn't tell you without seeing the full code but it looks like your variable "x4" on line e3 has not been declared anywhere.

Upvotes: 0

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