Hi, I’m still new to Julia, and am having problems with a for loop. I’m trying to create an array where each value is the former value minus another value. This is the code: for i = 1:T bal[i] = bal[i-1] - A[i] end where bal and A are arrays of the same size. The error I get is “MethodError…

That’s simple enough, although I’m not sure how it relates to what you’re trying to do in JuMP - what you’re trying to do works if you do it with regular numbers (e.g. Float64) rather than references: balance = zeros(10) balance[1] = 10 # initial amount owed amort = 1 # repayment per period julia> …

It would be great if you could provide an MWE - the error is telling you that for the type of variables you’re using, a subtraction operation is not defined, but without more context it’s hard to say where these types come from and why (if at all) you’d need them.

Oh alright, thanks for the link to the page as well. Here’s an MWE, I hope this would be enough. using JuMP m = Model() T = 300 @variables(m, begin delta0 >= 0 amort[i=1:T] >= 0 bal[0:T] >= 0 end) amort = delta0/T bal[0] = delta0 for i = 1:T bal[i] = bal[i-1] - amort end If there is …

Running your code seems to fail with a different error for me for i = 1:T bal[i] = bal[i-1] - amort end ERROR: MethodError: Cannot `convert` an object of type GenericAffExpr{Float64,VariableRef} to an object of type VariableRef Closest candidates are: convert(::Type{T}, ::T) where T at esse…

Oh alright, yeah I’m getting the same error too actually, and I sort of understand why it gives an error, but I’m not sure what else to do. I don’t think this particular issue is related to JuMP tho. So here’s basically what I want. Let’s say I have an amount of $10 at time period t = 0, and at the…

That is an impressive commitment to optimization - glad it works now!

For loop error

Specific Domains Optimization (Mathematical)

MuadhF July 10, 2019, 9:28am 7

Thank you! I completely forgot about trying regular numbers instead of JuMP variables.

Assigning JuMP VariableRef to an array position

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Assigning JuMP VariableRef to an array position Optimization (Mathematical)	6	1523	July 31, 2019
MethodError: no method matching -(::VariableRef, ::Nothing) General Usage question , jump , error	2	4350	March 3, 2020
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MethodError: no method matching zero(::Type{Vector{AffExpr}}) Optimization (Mathematical)	5	437	November 1, 2023

For loop error

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