Problem with using "subs"

[Zing]

Hi,

I am not able to do substitution of one expression into another. Can anyone tell me why. The last line of the code is throwing an error.

Thanks.

Ankur Sinha

P.S. I posted this message a while ago but am not able to see it in the topics. Apologies if this attempt leads to two posts.

from IPython.display import display, Math
from sympy import *

#Production
x = symbols('x')
#Tax
t = symbols('t')
#Level of automation (varies between 0 and 1)
l = symbols('l')

#Parameters
a,b,c,d,e,f,g,h = symbols('a b c d e f g h')
k,m,alpha = symbols('k m alpha')

#Solving firm's problem with automation tax
priceF = a - b*x
#Cost without automation
costWoutAutomation = d*x**2 + e*x + f

#Firm's profit
profitF = (1-alpha)*(priceF*x - costWoutAutomation)

#Solving
foc_x = diff(profitF,x)
optimal_x = solve(foc_x,x)

print(optimal_x)

print(optimal_x.subs(x,k))

[Aaron Meurer]

solve returns a list, so you need to use optimal_x[0] to get the first element.

But anyway, since you are solving for x, the result from solve does
not contain x, so the subs would do nothing.

Aaron Meurer

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[Zing]

 >>solve returns a list, so you need to use optimal_x[0] to get the first element.

Thanks a lot Aaron. This was helpful.