Sum of integers up to n using a while loop

Question

Will Murphy 2020-2-15

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/505673-sum-of-integers-up-to-n-using-a-while-loop

评论： Will Murphy 2020-2-15

Hi, I've recently started coding as part of my uni maths course, however I am struggling very much with the learning curve.

I want to know how to sum all the positive numbers up to and including n by using a while loop.

From what I have gathered already I would use in the case of n = 10

s = 0
n = 10 
while s < ((n + 1) * n / 2)
    N = N + 1
    s = s + N
end
disp(s)

What could I do to make this work? Any help would be greatly appreciated,

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Matt J 2020-2-15

Are we supposed to see why it doesn't work now?

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Answer 1

JESUS DAVID ARIZA ROYETH 2020-2-15

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/505673-sum-of-integers-up-to-n-using-a-while-loop#answer_415728

try it yourself with a for (see documentation)

https://www.mathworks.com/help/matlab/ref/for.html

You can be guided by this example:

s = 0;
k=1;
n = 10 ;
while k <= n
    s=s+k;
    k=k+1;
end
disp(s)

In the end, the idea is that with practice you can do all this code in a line like this:

n=10
s=sum(1:n)

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Turlough Hughes 2020-2-15

Line 4 is

while k <= n

k <= n is checking if the current value of k is less than or equal to n. If k is less than or equal to n then the condition is true and another iteration of the loop is implemented, if it is false, the loop is terminated.

Every time the loop is iterated, the value of k increases by 1 due to line 6

k = k+1;

It might help you to see the values as the loop progresses by running the following code:

s = 0;
k = 1;
n = 10 ;
while k <= n
    fprintf('Iteration Number: %d\n\nValues at start of iteration \nk = %d \ns = %d\n',k,k,s)
    s=s+k;
    k=k+1;
    fprintf('Values at end of iteration \nk = %d \ns = %d\n\n\n',k,s)
end