How to calculate a max value in a array without the built in functions.

The array is

Time = [1,6,3,6,8,12,1]

I think you need to use a for or while loop. There is no predetermined max value however as it is time.

Thanks.

Answer 1

[Mischa Kim]

Giuseppe, a for-loop would be the way to go:

 maxval = Time(1);
 for ii = 1:length(Time)
    if Time(ii) > maxval
        maxval = Time(ii);
    end
 end

Alternatively, you could use max(Time).

[Giuseppe]

thank you

[Tim Bigelow]

surely powerful MATLAB has a built in function that will find the maximum single element of an array? That is needed all the time!

[Steven Lord]

Of course it does. But the terms of the homework assignment (which Mischa's solution technically violates, as > is a built-in function) prohibit the use of built-in functions. This information is in the title of the original question, not the body. [Yes, technically the question doesn't state this was a homework assignment, but I've been on Answers and the MATLAB newsgroup before that for long enough to know a homework question when I read it.] Two such functions:

Time = [1,6,3,6,8,12,1];
[maxValue, maxLocation] = max(Time)
[maxValue2, maxLocation2] = maxk(Time, 1)

If you're willing to allow a bit more work:

[sortedTime, sortedIndices] = sort(Time, 'descend');
maxValue3 = sortedTime(1)
maxLocation3 = sortedIndices(1)

If Time were an array rather than a vector and you're using release R2018b or later of MATLAB, you can use max. Though if you want the linear index second output, you need to use release R2019a or later.

TimeA = reshape(randperm(4*5*6), [4 5 6]);
maxValue4a = max(TimeA, [], 'all')
[maxValue4b, maxLocation4b] = max(TimeA, [], 'all', 'linear')

I suspect the goal of the assignment was for the students to practice using loops to walk through the elements of an array, processing each element in turn as Mischa's solution does.

[manikanth Jonnadula]

Hey mate, can you help me how to find the Max Array from 5 identical Datasets using double For Loops please.

Answer 2

[Carlos]

A very easy newbie way to do it using a while loop (better with a for loop as Mischa states)

>> Time = [1,6,3,6,8,12,1];
>> max=Time(1);k=1;
>> while(k<=length(Time))
if(Time(k)>max)
max=Time(k);
end
k=k+1;
end

[Sean de Wolski]

Why is a while-loop better than a for-loop? You use a while loop when you don't know how many times it's going to have to run. Here you do, 1:numel(Time)

[Carlos]

I think you misunderstood what I have stated. I have pointed out it is a better practice to do this with a for loop(please read my answer again), but Giuseppe mentioned the possibility of implementing it with a while loop and that is the reason I posted the code with a while loop.

[Giuseppe]

thank you this is still useful. now i understand more about while vs for loops.

Answer 3

[Shivani Dixit]

You can use for loop or while loop for finding out the maximum or minimum element in the array without using any built-in functions.

Finding out maximum value in an array using for loop is shown below:

Time = [1,6,3,6,8,12,1];
ans = Time(1); % Initially take maximum element as first element and after iterating over the loop we will get final answer
for i=1:length(Time)
    if(Time(i)>ans)
        ans=Time(i);
    end
end
% The variable 'ans' would store the final maximum value