Strenghåndtering, primtall - lf

function res = isPalindrome ( str )
n = size (str , 2);
res = true ;
for i =1: n
    if str (i) ~= str (n+1-i)
        res = false ;
        break
    end
end
end

function res = sequenceFinder (sequence,start,stop )
len = 0;
index = 0;
for i = 1:length(sequence)-length(stop)
    if (length(start) <= length(sequence(i:end))) && strcmp(start,sequence(i:i+length(start)-1))
        indexS = i;
    elseif (length(stop) <= length(sequence(i:end))) && strcmp(stop,sequence(i:i+length(start)-1))
        indexE = i;
        if len < indexE -indexS
            len = indexE -indexS;
            index = indexS;
        end
    end  
end
res = sequence(index:index+len+length(stop)-1);
end

function a = isDevisable(a,b)
    a = ~mod(a,b);
end

function res = prime(a)
res = 1;
for b = 2:a-1
    if isDevisable(a,b)
        res = 0;
        break;
    end
end
end
function a = isDevisable(a,b)
    a = ~mod(a,b);
end

function res = prime(a)
res = 1;
if isDevisable(a,2)
    res = 0;
    return;
end
for b = 3:ceil(sqrt(a)) 
    if isDevisable(a,(2*b+1))
        res = 0;
        break;
    end
end
end