Write a Matlab script that asks for an integer (n) and then computes the following based on the value of the integer:

While the value of n is greater than 1, replace the integer with half of its value (n/2) if the integer is even. Otherwise, replace the integer with three times its value, plus 1 (3*n + 1).

Print the sequence that results.

Example: if n=10 then the sequence will be 10, 5, 16, 8, 4, 2, 1

[Ingrid]

when posting homework questions you should at least also show the code that you have tried so far and indicate where you got stuck

[Purushottama Rao]

As i understood from the question, you would like to input an interger say 10, and you would like to generate a sequence. Is the sequence should consider 1 to 10 numbers for the above said arithematics. Then in that case for a given integer say 10, the sequence conatins 10 elements? is that what you want to do?

Answer 1

[Ingrid]

prompt = 'Give an integer value? ';
n = input(prompt);
% check if integer number is provided
if ~(abs(round(n)-n) < eps)
 errordlg(' The number provided is not an integer');
else
while n > 1

if floor(n/2) == n/2
%number is even
n = n/2;
else
%number is odd
n = 3*n+1;
end
disp(n)
end
end

this took about 1 minute so should not have been too difficult to solve yourself

[Guillaume]

"this took about 1 minute so should not have been too difficult to solve yourself", so it would be best no to give away the whole solution without seeing at least some sort of attempt by the OP.

Answer 2

[Purushottama Rao]

k=input('enter the data')
a=1:k;
disp('before manipulations')
disp(a)
for n=1:length(a)
if (a(n)>1&&mod(a(n),2)==0)
a(n)=0.5*a(n);
elseif (a(n)>1 && mod(a(n),2)==1)
a(n)=3*a(n)+1;
end
end

enter the data 10

k =

    10

before manipulations 1 2 3 4 5 6 7 8 9 10

after manipulations 1 1 10 2 16 3 22 4 28 5 disp('after manipulations') disp(a)

[Purushottama Rao]

I still doubt whether you are looking for some kind of this. If not give whhat kind of input you have and expected output clearly

[Guillaume]

I don't think that you've answered the problem correctly (my feeling is that it is to test the student's understanding of while loops), but if you were to do it like this, using vectorised operations would be better:

a = 1:k
evenvalues = mod(a, 2) == 0;
a(evenvalues) = a(evenvalues) / 2;
oddnotone = a > 1 & mod(a, 2) == 1;
a(oddnotone) = 3 * (a(oddnotone) + 1);

In any case, avoid giving complete solution to obvious homework problem. The student will just end up submitting your solution without even bothering understanding it, so will learn nothing.

[Ingrid]

I do not think this is what requested since you do not know how many elements the solution will have on beforehand

when the integer is 15 the solution is for example

46 23 70 35 106 53 160 80 40 20 10 5 16 8 4 2 1

so seventeen elements, hence requiring a while loop to check if the resulting integer is still larger than one

[Purushottama Rao]

I think the way the question asked is somewhat confusing to me. Looking at the exapmle if the input is 10, then how can he have a sequence of no.. Acoordig to your code it must be a single value 5. But it has been indiated that the sequence is expected...

[Guillaume]

I thought that was pretty clear. The first element of the sequence is the input number, the next element is either:

• half the previous element, if it is even
• 1 plus 3 times the previous element, if it is odd and greater than one
• the end of the sequence, if it is 1.