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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 = 1:2:ceil(sqrt(a)) 
    if isDevisable(a,b)
        res = 0;
        break;
    end
end
end

les = fopen('prim.txt','r');
if les ==-1
    break;
end
A = fscanf(les,'%f');
if isempty(A)  % Om filen er tom skriver vi '2' inn i den.
    x = 2;
    A(1)= 2;
    skriv = fopen('prim.txt','w');
    fprintf(skriv, '%20f\r\n',x);
else %  Ellers skriver vi inn alt,
    skriv = fopen('prim.txt','w');
    x = A(end);
    fprintf(skriv, '%20f\r\n',A);
end
while (length(A) < 1500200)
    
    x = x + 1;
    i=1;
    prime = 1;
    while sqrt(x)>= A(i)
        if x/A(i) == floor(x/A(i))
            prime = 0;
            break;
        end
        i = i+1;
    end
    
    
    if prime % Legger det til i listen, og til filen.
        fprintf(skriv, '%20f\r\n',x);
        A = [A; x];
    end
end
fclose('all');