Loop not working to find min,max,mean

I am running a for loop to determine the min,max, and mean of a DNA sequence. When I try to run the program it outputs zero as the value of the min max and mean. I can't find a solution to why the loop is not running properly. Does anyone have a fix?

load('chr1_sect.mat')
numBases = length(dna);
startPoint = 0; nump = 0;
for k = 1:3:numBases-2
    if startPoint == 0
        if dna(k) == '1' && dna(k+1) == '4' && dna(k+2) == '3'
            startpoint = k; 
        end
    else
        if ((dna(k)) == '4' && dna(k+1) == '1' && dna(k+2)) == '1' ||...
            (((dna(k))) == '4' && dna(k+1) == '1' && dna(k+2)) == '3' ||...
            (((dna(k))) == '4' && dna(k+1) == '3' && dna(k+2)) == '1'
            nump = nump +1;
            SavedPoints(np,1) = startPoint;
            SavedPoints(np,2) = k;
            startPoint = 0;
        end
     end
end

x = min(nump)
y = max(nump)
z = mean(nump)

[Stephen Cobeldick]

Note that you can probably replace those repeated logical operations e.g.:

dna(k) == '1' && dna(k+1) == '4' && dna(k+2) == '3'

with simpler

strcmp(dna(k:k+2),'143')

or

isequal(dna(k:k+2),'143')

Answer 1

[Geoff Hayes]

Marios - from your code

nump = nump +1;

will always be a scalar (1x1) value which seems incorrect. Should this be an array of values? As for why, nump is always zero

    if startPoint == 0
        if dna(k) == '1' && dna(k+1) == '4' && dna(k+2) == '3'
            startpoint = k; 
        end
    else

note how the condition is for startPoint == 0 but you then initialize startpoint = k....which is a different variable because of the lower-case p. Try changing this to

    if startPoint == 0
        if dna(k) == '1' && dna(k+1) == '4' && dna(k+2) == '3'
            startPoint = k; % <---- note the difference
        end
    else

and see what happens.

[Marios Christofides]

Thank you. How should I change nump to be a vector while still being updated?

[Geoff Hayes]

Marios - what are you trying to save on each iteration of the loop?