From this

import sympy as sp

x,y,z = sp.symbols("x y z")
sp.Ep(x,y/z)

To this

#varibles = array
#equation = ????
def solver(variables,equation):
    #Looping through variables array and converting variables to sympy objects 
    for var in variables:
        var = sp.symbols(var)
    
    #Generate sympy Equation
    equation = sp.Ep(equation)

variables = [x,y,z]
equation = x,y/z #invalid code

solver(variables,equation)

I'm creating a function that is able to take in an equation with x amount of variables and x-1 number of values then solve for the missing variable symbolically then return a numerical answer using the values provided.

I only included a small portion of code where I'm having trouble understanding how to pass through an equation. Any solutions or pointers would be greatly appericated. Thanks.

CodePudding user response：

There are several layers of potential confusion here concerning Python variables and SymPy objects (Symbols) used for variables.

Here is an example of what you are saying:

# 3 variables
syms = x, y, z = var('x:z')
# 2 values
vals = {x:1, y:2}
# an equations
eq = Eq(x, y/z)

# solve for the missing value symbolically
missing = set(syms) - set(vals)  # == {z}
solve(eq, missing)
[y/x]

# solve for the missing value after substituting in the known values
solve(eq.subs(vals))
[2]

You could make a solver to accept an equation and then specified values and figure out the missing one and return that value by doing something like this:

>>> def solver(eq, **vals):
...     from sympy.core.containers import Dict
...     from sympy.solvers.solvers import solve
...     free = eq.free_symbols
...     vals = Dict(vals)
...     x = free - set(vals)
...     if len(x) != 1:
...         raise ValueError('specify all but one of the values for %s' % free)
...     x = x.pop()
...     return solve(eq.subs(vals), x, dict=True)
...
>>> solver(eq, x=1, z=2)
[{y: 2}]

Does that give you some ideas of how to continue?