an error to find maximum index in array in MATLAB

Question

I want to make an array 15*15 and fill them with these code and I want to find max of a row of it. I wrote this codes in MATLAB to make an array:

a = zeros (15) - inf;

for i=1:15 
    k2=4;
    l2=1;

    k=floor((i-1)/3);
    l=mod((i-1),3);
    f=false;
    if (k==k2 && abs(l2-l)==1)
        f=true;
    end
    if(l==l2 && k2-k==1)
        f=true;
    end
    if(k2-k==1 && abs(l2-l)==1)
        f=true;
    end

    if (f)
        a(i,14)=100;
    end
end
max=200;
for i=1:15
    if(find(2,i) < max)
        max=i;
    end
end

max=0

when I wrote these codes to find maximum index in 2nd row of array this error shown:

b=a(2,:)

b =

     1  -Inf     1     1     1     1  -Inf  -Inf  -Inf  -Inf  -Inf  -Inf  -Inf  -Inf  -Inf

>> [~,index]=max(b)
??? Indexing cannot yield multiple results.

yes , after zeros ... I fill array (a) with -inf by 2 for loop. — Sajjad Rostami
– Sajjad Rostami, Commented Feb 28, 2013 at 7:18
BTW you can create a matrix of -Inf just by subtracting inf from the zeros matrix so you don't need the loops. I have edited your code to reflect this. — Dan
– Dan, Commented Feb 28, 2013 at 7:24
@Dan: what is your edit of the code good for? The line zeros (15,15) - inf; does not make sense at all when the created array is not assigned to a variable. — H.Muster
– H.Muster, Commented Feb 28, 2013 at 8:47
@H.Muster Yes you are correct. I did not notice that the original question just had zeros assigned to nothing. It should be a = zeros(15) - inf; based on the OPs comment above. — Dan
– Dan, Commented Feb 28, 2013 at 9:00

yuk · Accepted Answer · 2013-02-28 07:25:15Z

3

You have variable max and trying to use function max.

It's a good practice to check for existing names with exist var_name or which var_name command.

Rename your variable max in the code and remove it from the workspace with clear max.

edited Feb 28, 2013 at 7:25

answered Feb 28, 2013 at 7:16

yuk

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3 Comments

yuk Over a year ago

What to explain. You define variable in max=200. Then trying to call function max. In MATLAB variable indexing and function call have the same syntax. Function can produce multiple outputs, but indexing cannot.

Dan Over a year ago

Matlab doesn't know if you want to use the function max() or the variable you created called max. Basically just give your variable max a different name.

yuk Over a year ago

@Dan: yes, forgot to mention this.

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