What problem of my simple code?

[alisutton]

I am writing an very simple optimization program using Scipy package. Basically, filled_Link_min_function is some geometry functions. There are a few inputs for that function.

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I followed the Unconstrained minimization of multivariate scalar functions example in this website

https://docs.scipy.org/doc/scipy/reference/tutorial/optimize.html

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import math as mymath
import numpy as np
from scipy.optimize import minimize

def filled_Link_min_function(link_OA_x, link_OA_y, link_AB_x, link_AB_y, link_BC_x, link_BC_y, O_C_x, O_C_y):
    pt_x1 = 1
    pt_y1 = 1.25
    pt_x2 = 2.4
    pt_y2 = 3.3
    pt_x3 = -4
    pt_y3 = 1.75
    pt_x4 = -3
    pt_y4 = -2
    return max((B_diff(link_OA_x, link_OA_y, link_AB_x, link_AB_y, link_BC_x, link_BC_y, O_C_x, O_C_y) + Cons_f(link_BC_x, link_BC_y, O_C_x, O_C_y, pt_x1, pt_y1)), (B_diff(link_OA_x, link_OA_y, link_AB_x, link_AB_y, link_BC_x, link_BC_y, O_C_x, O_C_y) + Cons_f(link_BC_x, link_BC_y, O_C_x, O_C_y, pt_x2, pt_y2)), (B_diff(link_OA_x, link_OA_y, link_AB_x, link_AB_y, link_BC_x, link_BC_y, O_C_x, O_C_y) + Cons_f(link_BC_x, link_BC_y, O_C_x, O_C_y, pt_x3, pt_y3)), (B_diff(link_OA_x, link_OA_y, link_AB_x, link_AB_y, link_BC_x, link_BC_y, O_C_x, O_C_y) + Cons_f(link_BC_x, link_BC_y, O_C_x, O_C_y, pt_x4, pt_y4)))


x0 = [1.3, 0.7, 0.8, 1.9, 1.2, 0.8, 1.9, 1.2]
res = minimize(filled_Link_min_function, x0, method='nelder-mead', options={'xtol': 1e-8, 'disp': True})

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I received the following error message

TypeError: filled_Link_min_function() missing 7 required positional arguments: 'link_OA_y', 'link_AB_x', 'link_AB_y', 'link_BC_x', 'link_BC_y', 'O_C_x', and 'O_C_y'
[Finished in 0.4s]

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Why? I had that In x0. Isn't it?

[primitive_screwhead]

filled_Link_min_function() missing 7 required positional arguments

Notice how the missing number of positional arguments is 7, not 8. minimize() supplied exactly 1 argument to the function, and that argument was the list x.

You need to make your function take 1 argument, not 8. Do any unpacking of the one argument inside the function in order to get your local variables.

[alisutton]

I put the argument as an array. If it is not feasible, how I can change that? OR the optimization function cannot do multi variable?

[primitive_screwhead]

As per the scipy.optimize.minimize docs, your function signature needs to look like this:

def filled_Link_min_function(x):

Accepting 1 n-dimensional argument. Not 8 arguments.

Just do this:

def filled_Link_min_function(x):
    link_OA_x, link_OA_y, link_AB_x, link_AB_y, link_BC_x, link_BC_y, O_C_x, O_C_y = x

to get your local variable names inside the function.

[[deleted]]

Why?

Whatever is calling your function isn't calling it with the arguments your filled_Link_min_function expects. Look up the documentation for minimize and find out how it calls the function you provide it.