Sub-Function help!

I have a homework that I don't understand. This what it says

You need to make a function of [A,B] = mystatistic(Scores).

A = (average of Test 1 ) * (standard deviation of Test 3)

B = (median value of Test2) / (average of Test2)

(1) Use of sub-function

(2) Use of inline function for the sub function

I am not sure how to do [A,B] = mystatistic(Scores). Also I know what is a sub-function but I don't get it here.

Your help is highly appreciated.

Answer 1

[MHN]

Based on the question it seems "Scores" is a N*3 matrix (N shows number of students). You should write a function that outputs A and B. So your main function will look like

function [A,B] = mystatistic(Scores)
      %Calculation
end

To test your program use the following Score as an example (N=10)

Scores = randi(100,10,3) %let assume the exam is out of 100

Now, try the code yourself and if you have question let us know. We are not going to solve your assignment! ;)

[Jay]

Thank you for your answer. Here what I got and I don't know what I am doing. Please guide me

function [A,B] = mystatistic(Scores)

fid = fopen('TestScoresKim.txt','r'); % open file

headings = fgetl(fid); fgetl(fid); Scores = fscanf(fid,'%f'); Scores = reshape(Scores,[4 20])'; display(Scores);

Test1 = Scores(:,2); Test2 = Scores(:,3); Test3 = Scores(:,4);

A = ((mean(Test1)) * (std(Test3))) B = (median(Test2)) * (mean(Test2))

end

[MHN]

function [A,B] = mystatistic(Scores)

fid = fopen('TestScoresKim.txt','r'); % open file
headings = fgetl(fid); % read the first line
fgetl(fid); % ignore the second line
Scores = fscanf(fid,'%f'); % read the numbers in the text file
Scores = reshape(Scores,[4 20])'; % put those numbers in a 20*4 matrix
display(Scores);

Test1 = Scores(:,2); %2nd column shows test1
Test2 = Scores(:,3); %3rd column shows test2
Test3 = Scores(:,4); %4th column shows test3

A = ((mean(Test1)) * (std(Test3))) % compute A
B = (median(Test2)) * (mean(Test2)) % compute B

end

But you should also used subfunction, for example you can write the code for mean by yourself (just a loop which sum up the elements of a vector divided by size).