I am facing some syntex error when going to run this code

Answered

Abu Hashan Md Mashud

March 21, 2023 01:44

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import gurobipy as grb

# Define the function TC_c1M
Cp = 1
Cmgc = 2
P1 = 40
K = 0.5
D = [1, 2, 3]
tfix = 1
delta = 0.5
tv = 1
Td = 2
WN = 3
C1 = 4
C2 = 5
Vf = 6
N = 100
L = 50
Qs = 600
vera = 5
tm1 = .3

# Create a Gurobi model instance
m = grb.Model()

# Define decision variables
T = m.addVar(lb=1, ub=200, name="T")
x1 = m.addVar(lb=0, ub=3, name="x1")

def costFunction(D, T, x1, tm1,H):
    total = 0
    for i in range(len(D)):
        value = D[i] *H 
        H=(0.5 * x1**2 * T**2 - x1 * T * tm1 + 0.5 * tm1**2)
        total += value
    return total

def thetafunction(vera, N, L, A):
    deno = 0
    for i in range(0, L):
        val = vera**i + (N-L) * vera**(L-1)
        deno += val
    outp = A / deno
    return outp

theta = thetafunction(vera, N, L, Qs)

def TCc1M(T, x1):
    term1 = Cp * Qs + Cmgc * (Qs * T - 0.5 * (1 - K) * P1 * T**2 + H2
    H2=costFunction(D, T, x1, tm1))
    term2 = tfix * Qs + (2 * delta * tv * Qs * Td * WN) / (C1 * Vf) + (2 * (1 - delta) * tv * Qs * Td * WN) / (C2 * Vf)
    return term1 + term2 

# Set objective
m.setObjective(TCc1M(T, x1), grb.GRB.MINIMIZE)

# Optimize the model
m.optimize()

# Print the optimal solution
print("Optimal solution:")
for v in m.getVars():
    print(v.varName, v.x)

Related to

• Syntax Error

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• 

  Riley Clement

  • Gurobi Staff

  March 21, 2023 01:54

  Hi Abu,
  
  Your parentheses don't match up on these two lines

  term1 = Cp * Qs + Cmgc * (Qs * T - 0.5 * (1 - K) * P1 * T**2 + H2
  H2=costFunction(D, T, x1, tm1))

  
  - Riley

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  Abu Hashan Md Mashud

  March 21, 2023 02:01

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  Thanks. I have changed the code like:

  import gurobipy as grb

  # Define the function TC_c1M
  Cp = 1
  Cmgc = 2
  P1 = 40
  K = 0.5
  D = [1, 2, 3]
  tfix = 1
  delta = 0.5
  tv = 1
  Td = 2
  WN = 3
  C1 = 4
  C2 = 5
  Vf = 6
  N = 100
  L = 50
  Qs = 600
  vera = 5
  tm1 = .3

  # Create a Gurobi model instance
  m = grb.Model()

  # Define decision variables
  T = m.addVar(lb=1, ub=200, name="T")
  x1 = m.addVar(lb=0, ub=3, name="x1")

  def costFunction(D, T, x1, tm1):
      total = 0
     
      for i in range(len(D)):
          H=(0.5 * x1**2 * T**2 - x1 * T * tm1 + 0.5 * tm1**2)
          value = D[i] *H 
          total += value
      return total

  def thetafunction(vera, N, L, A):
      deno = 0
      for i in range(0, L):
          val = vera**i + (N-L) * vera**(L-1)
          deno += val
      outp = A / deno
      return outp

  theta = thetafunction(vera, N, L, Qs)

  def TCc1M(T, x1):
      H2=costFunction(D, T, x1, tm1)
      term1 = Cp * Qs + Cmgc * (Qs * T - 0.5 * (1 - K) * P1 * T**2 + H2)
      
      term2 = tfix * Qs + (2 * delta * tv * Qs * Td * WN) / (C1 * Vf) + (2 * (1 - delta) * tv * Qs * Td * WN) / (C2 * Vf)
      return term1 + term2 

  # Set objective
  m.setObjective(TCc1M(T, x1), grb.GRB.MINIMIZE)

  # Optimize the model
  m.optimize()

  # Print the optimal solution
  print("Optimal solution:")
  for v in m.getVars():
      print(v.varName, v.x)

   

  But still errors like this showing:

  
    File "src\gurobipy\quadexpr.pxi", line 257, in gurobipy.QuadExpr._mul

  GurobiError: Invalid argument to QuadExpr multiplication

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• 

  Riley Clement

  • Gurobi Staff

  March 21, 2023 02:22

  Hi Abu,

  There is a lot which needs fixing here and I think you are missing the basics of modelling with Gurobi.
  
  Firstly, you have not defined any constraints.  It would be useful for you to consult several of our examples in order to get a solid foundation for how to define models with Gurobi.

  Secondly, you cannot perform the square of a variable with v, using v**2.  You need to either use v*v or for more general powers use addGenConstrPow.
  
  Thirdly, you cannot directly multiply more than two variables together, but you can use auxiliary variables to achieve the result.  See this community post for more details.

  - Riley

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