Test Results: Incorrect! 1.Does maxIndices exist? 2.Is findquakes defined correctly? 3.Is the x-axis data correct?

[Venkatbabu]

[DGM]

Seems multiple people are having this same problem today.

https://www.mathworks.com/matlabcentral/answers/2021321-issue-with-signal-processing-onramp-course-code-submission

https://www.mathworks.com/matlabcentral/answers/2021236-i-have-faced-an-issue-while-completing-signal-processing-onramp-course-on-matlab

https://www.mathworks.com/matlabcentral/answers/2021176-signal-processing-onramp-signal-measurements-answer-incorrect-even-though-the-code-is-correct-acc

https://www.mathworks.com/matlabcentral/answers/2021446-test-results-incorrect-1-does-maxindices-exist-2-is-findquakes-defined-correctly-3-is-t

Answer 1

[Renee Coetsee]

Thank you for reporting this issue. This is a known bug and we are actively working on fixing it in the course.

In the meantime, the workaround for Task 4 to

1. Click See Solution (left of the Submit button)
2. Copy the entire solution from the solution script into the working script
3. Submit Task 4

If that doesn't work, copy and paste the following code for Task 4:

% Find local maxima
maxIndices = islocalmax(pwr,"SamplePoints",t);
% Display results
figure
plot(t,pwr,"Color",[77 190 238]/255,"DisplayName","Input data")
hold on
% Plot local maxima
plot(t(maxIndices),pwr(maxIndices),"^","Color",[217 83 25]/255,...
    "MarkerFaceColor",[217 83 25]/255,"DisplayName","Local maxima")
title("Number of extrema: " + nnz(maxIndices))
hold off
legend
xlabel("t")

Then in Task 5, Reset the script (left of the Submit button) and complete Task 5 normally.