Product Perfect

The General Algebraic Modeling System (GAMS) is a high-level modeling system for mathematical optimization. Developed in 1976 by Alexander Meeraus, it is designed for modeling and solving linear, nonlinear, and mixed-integer optimization problems. GAMS provides a stable and intuitive environment for complex applications, offering a tailored syntax and structure for specifying optimization models. It is widely used in economic modeling, energy planning, and other scientific fields that require advanced mathematical computation. The information about GAMS can be found on its official website and various scholarly articles on computer programming languages.

Ask the right questions secure the right GAMS talent among an increasingly shrinking pool of talent.

First 20 minutes

General GAMS app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in GAMS application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you define GAMS?

GAMS, or General Algebraic Modeling System, is a high-level modeling system for mathematical programming and optimization. It is designed for modeling and solving linear, nonlinear, and mixed-integer optimization problems.

What are the key features of GAMS?

GAMS offers a flexible and intuitive syntax, supports a wide range of solver engines, provides tools for model analysis and debugging, and allows for easy integration with other software and databases.

Describe the difference between a scalar and a parameter in GAMS.

In GAMS, a scalar is a single number, while a parameter is a multidimensional array of numbers. Both can be used to represent constant values in a model, but parameters are more flexible as they can represent different values depending on their indices.

How would you declare a set in GAMS?

In GAMS, a set is declared using the 'set' keyword followed by the set name and an explanatory text. For instance, 'set i 'index set'' would declare a set named 'i'.

What are the different data types in GAMS?

GAMS supports several data types, including scalars, parameters, variables, equations, sets, and model types.

The hiring guide has been successfully sent to your email address.

Oops! Something went wrong while submitting the form.

What you’re looking for early on

Does the candidate have a strong understanding of GAMS language?

Has the candidate demonstrated problem-solving skills?

Is the candidate able to communicate effectively?

Does the candidate have experience with optimization models in GAMS?

Next 20 minutes

Specific GAMS development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

Describe the difference between a variable and an equation in GAMS.

In GAMS, a variable represents an unknown value that the model tries to determine, while an equation represents a mathematical relationship between variables and parameters. Variables can be decision variables or objective function variables, and equations usually represent constraints in the model.

How would you define an equation in GAMS?

In GAMS, an equation is defined using the 'equation' keyword followed by the equation name and an explanatory text. The actual mathematical expression of the equation is defined separately, using the equation name, the domain over which the equation is defined, and the mathematical expression itself.

What are the different types of variables in GAMS?

GAMS supports several types of variables, including free variables, positive variables, binary variables, integer variables, and non-negative variables.

Describe the difference between a free variable and a positive variable in GAMS.

In GAMS, a free variable can take any real value, including negative values, zero, or positive values, while a positive variable can only take non-negative values.

How would you solve a model in GAMS?

To solve a model in GAMS, you would first need to define the model using the 'model' keyword, and then use the 'solve' statement, specifying the model name, the type of model (LP, NLP, MIP, etc.), and the variable to be optimized.

The hiring guide has been successfully sent to your email address.

Oops! Something went wrong while submitting the form.

At this point, a skilled GAMS engineer should demonstrate strong problem-solving abilities, proficiency in GAMS programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with GAMS.

What does this simple GAMS code do?
Set i /1*5/;
Parameter p(i);
p(i) = ord(i);
Display p;
This code defines a set 'i' of 5 elements, creates a parameter 'p' indexed over the set 'i', assigns each element of 'p' its ordinal value within the set, and then displays the values of 'p'.
What will be the output of this GAMS code snippet?
Set i /1*3/;
Parameter p(i);
p('1') = 5;
p('2') = 10;
p('3') = 15;
Display p.sum(i, p(i));
This code will output the sum of the elements of the parameter 'p', which is 30.
What does this GAMS code snippet do?
Set i /1*5/;
Parameter p(i);
loop(i, p(i) = sqr(ord(i)););
Display p;
This code defines a set 'i' of 5 elements, creates a parameter 'p' indexed over the set 'i', assigns each element of 'p' the square of its ordinal value within the set using a loop, and then displays the values of 'p'.
What will be the output of this GAMS code snippet?
Set i /1*3/;
Parameter p(i);
p('1') = 5;
p('2') = 10;
p('3') = 15;
option threads = 2;
Display p.sum(i, p(i));
This code will output the sum of the elements of the parameter 'p', which is 30. The 'option threads = 2;' statement sets the number of threads to be used by GAMS, but does not affect the output in this case.

Wrap-up questions

Final candidate for GAMS Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle GAMS application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What are the different ways to input data into a GAMS model?

Data can be input into a GAMS model in several ways, including directly in the model file, from external files, from databases, or from spreadsheets.

Describe the difference between a loop and a conditional statement in GAMS.

In GAMS, a loop is used to repeatedly execute a block of code, while a conditional statement is used to execute a block of code only if a certain condition is met. Both can be used to control the flow of execution in a GAMS program.

How would you handle errors in GAMS?

Errors in GAMS can be handled by carefully reading and interpreting the error messages provided by the GAMS compiler and runtime system, and by using the debugging and model inspection tools provided by GAMS.

GAMS application related

Product Perfect's GAMS development capabilities

Beyond hiring for your GAMS engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in GAMS projects, and can engage in multiple capacities.

GAMS Consultive assessments

GAMS Application Conversion Assessment GAMS Application Integration Assessment GAMS Data & Database Integration Assessment

Custom GAMS development projects

Custom GAMS App Conversion GAMS Custom App Development Process App UI Design for GAMS Facelifts

Hiring guide for GAMS Engineers

GAMS Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

What you’re looking to see on the GAMS engineer at this point.

GAMS Consultive assessments

Custom GAMS development projects