Using a function with a loop for finding the maximum value and its index.

Hello!

I am fairly new to MATLAB and am struggling with the topic of loops. A homework of mine is the following:

I need to write a function that finds the max value and its index in a data vector. Also, I am not allowed to use the built-in max function or any other function that relates to the order of magnitudes of elements.

So far I have this function:

function[Max1, MaxI1] = VecMax(Vec1)
Max1 = Vec1(1);
MaxI1 = 1;
while (MaxI1 < length(Vec1))
    if(Vec1(MaxI1) > Max1)
        Max1=Vec1(MaxI1);
    end
    MaxI1 = MaxI1 + 1 ;
end
end

Using this example

Vec1=[4 5 9 2 10 -1 4 0 3 12 4];
[Max1,MaxI1] = VecMax(Vec1);

I receive the correct Value for Max1 but still having issues with MaxI1.

Help would be really appreciated

Answer 1

[David Hill]

Vec1=[4 5 9 2 10 -1 4 0 3 12 4];
[Max1,MaxI1] = VecMax(Vec1)

Max1 = 12

MaxI1 = 10

function[Max1, MaxI1] = VecMax(Vec1)
Max1 = Vec1(1);
MaxI1 = 1;
for k=2:length(Vec1)%use for-loop to cycle through entire array
    if Vec1(k) > Vec1(k-1)
        Max1=Vec1(k);
        MaxI1=k;
    end
end
end

[Mike]

Thank you!

But a following up question why does this code not work for this example?

As a solution I get Max1 = 99 , MaxI2 =6

Vec1=[-100 0 200 30 50 99];
[Max1,MaxI1] = VecMax(Vec1)

[Torsten]

Vec1=[-100 0 200 30 50 99];
[Max1,MaxI1] = VecMax(Vec1)

Max1 = 200

MaxI1 = 3

function[Max1, MaxI1] = VecMax(Vec1)
  Max1 = Vec1(1);
  MaxI1 = 1;
  for k=2:length(Vec1)%use for-loop to cycle through entire array
    if Vec1(k) > Max1
        Max1=Vec1(k);
        MaxI1=k;
    end
  end
end

[David Hill]

Yes!

[Mike]

You guys are awesome! Thanks