# Tag Info

12

Excel remains extensively used in industry for non-OR applications. That means that if you are doing an OR application that does not require access to a database, there's a good chance the data for the application will come to you in either an XLSX or CSV file. On the flip side, when it comes time to convey the solution provided by your application, it is ...

7

Many many people know Excel and use Excel. So many OR projects start with some Excel spreadsheet. And that is why being able to read from and write to Excel is key. You may even start the project with the Excel solver. Moreover Excel is a common tool when companies choose plugin optimization instead of packages, custom or tailored optimization.

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For the first question, suppose you somehow knew which days would be production days and fixed the values of the $z_t$ variables accordingly, while allowing $q_t$ and $i_t$ to be continuous variables. You would be left with a "flow" type linear program. Since the capacities and demands are integer-valued, your flow LP would automatically produce ...

4

There are different solvers in Excel that are suited for different types of problems: Simplex LP GRG Nonlinear Evolutionary The Simplex LP solver is the only solver that can guarantee an optimal solution, however, the problem size is somewhat limited and all of the constraints as well as the objective function have to be linear. Your problem is small, ...

2

Consider the following LP: \begin{align*} \max\,3x_{1}+5x_{2}\\ \textrm{s.t. }x_{1}+2x_{2} & +s_{1}=3\\ 2x_{1}+x_{2} & +s_{2}=3\\ x_{1}+x_{2} & +s_{3}=2\\ x,s & \ge0 \end{align*} ($s$ being slack variables). The feasible region has corners (0, 0), (0, 1.5), (1, 1) and (1.5, 0), with (1, 1) the unique optimum. If you choose the \$(x_1, x_2, s_3)...

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The problem is feasible only if the sum of the rows equals the sum of the columns. That's true for your Reference table, but not for the other tables. I'm not clear about what your objective function is intended to do relative to the Reference table. But your formula =((SUM(B19:F31))^2)^(1/2) makes no sense. Perhaps you intend to sum the squared differences ...

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Don't get hung up on having to use Excel - many off-the-shelf software packages don't even begin to address the issues job shops have. Excel is a great way to experiment and develop a system that works without spending a small fortune in the process. Speaking of the process, it is often useful to apply the Theory of Constraints to your business, and use it ...

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I managed to understand why the pace of building up the model using Open Solver slows down after a while. The reason is because there were several (in)equations without values, which was why model building was initially fast.

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As far as I know, SCIP has presented some useful solutions to deal with it. First, by using an interactive shell, which I don't know has the capability to connect with the separate sheet software like excel. The second, by using a low-level API like C/C++, python, etc. I think you could write your own model in your favorite language through the many ...

1

There are a lot of good answers above if you are willing to develop your own model and visualisations. There’s also an app that I’d recommend: https://www.modelandoptimize.com It has a simple interface and I think your use case can be represented by their Job Scheduling demo. They provide the solution in excel if you like.

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