MATLAB Grader. How to check vectroization in students solution?

SolutionFile = fileread('solution.m');
if ~contains(SolutionFile,'(1:5).^(5:-1:1)')
    error('You did not vectorized the code as intended, please refer to the following example...')
end

or something less specific to allow alternative solutions:

if ~contains(regexprep(SolutionFile,'\s',''),'.^')
    error('You did not used the elementwise power operator')
end

or

MaxNumber = 4;
NumberOfPowerOperators = numel(strfind(SolutionFile,'^'));
if NumberOfPowerOperators>MaxNumber
    error('You used the power operator to often, it seems you did not vectorized your code properly')
end

Using splitlines and a loop you could also check each line for the amount of used operators. However, even if you write a complex test you cannot consider all possible solutions by the students. But a few lines of code may help you to identify strange solutions for a manual review.

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Answer 1

Cris LaPierre 2020-3-27

2
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https://ww2.mathworks.cn/matlabcentral/answers/513208-matlab-grader-how-to-check-vectroization-in-students-solution#answer_422192

编辑：Cris LaPierre 2023-10-10

在 MATLAB Online 中打开

There is no built-in way to check that they used element-wise operators (.^).

You can prohibit the use of the keyword for, to avoid their solving it with a for loop.

My suggestion would be to assign the number to use randomly. That way, they can't hardcode their solution.

% provide the following as locked line in the student template
n = randi([4,10]);
% Student provides their solution underneath
x=(1:n).^(n:-1:1);

Because the reference and learner solutions share the same random number seed, the reference solution would just be

n = randi([4,10]);
x=(1:n).^(n:-1:1);

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Cris LaPierre 2020-3-27

编辑：Cris LaPierre 2020-3-27

Let me recommend our Teaching with MATLAB self-paced course. I'd suggest quickly browsing all the chapters, as they all focus on our resources for teaching online. Chapter 6 in particular covers MATLAB Grader.

Also, Grader comes with some pre-built problems. The Getting Started with MATLAB Grader collection was specifically designed to help you get started. The last page of the Teaching with MATLAB course contains a table that helps identify problems to use as a template for common requests (working with files, random numbers, etc). For example, look at the Coordinate transformations Navigating a robot problem to see how you can use random numbers to create variables for your students to use.

Cris LaPierre 2020-3-27

Grader is essentially a variable checker. It is not a good solution for interactive/gui exercises. It should work well for your laboratories provided the code does not cause grader to time out (<1 minute to run and assess code).

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