Loop and input question

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John Colley
John Colley 2015-10-11
回答： Maneet Kaur Bagga 2022-7-5
I need to create a loop that ask for s user inputed number and then adds odds number starting at 1 until target number is reached.
  2 个评论
Image Analyst
Image Analyst 2015-10-12
OK. Good luck with that. Feel free to post your code and ask a question after reading this if you need help.
Image Analyst
Image Analyst 2015-10-12
What's an "odds number"? Do you mean odds, as in chance or probability? Maybe use rand() or randn(). Or did you mean "an odd number" like 1,3,5,7, etc.? If so, which number? Or do you need to ask the user for one?

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回答（2 个）

Stalin Samuel
Stalin Samuel 2015-10-12
%If you are trying to find the sum of all odd no's between 1 and s (i.e s is your limit )
prompt = 'What is the value of s? ';
s = input(prompt)
O_Sum = 1
for i = 2:s
if mod(i,2)
O_Sum = O_Sum +i
end
end
  1 个评论
Stephen23
Stephen23 2015-10-12
This is a very inefficient loop: only half of the iterations actually perform anything useful. Rather than wasting lots of iterations, MATLAB easily iterates only over the odd values only, which means that the if statement is also not required:
s = input('What is the value of s? ','s');
x = 0;
for k = 1:2:str2double(s)
x = x+k;
end
Of course the whole thing would in any case be much neater and faster by using MATLAB's code vectorization abilities, which reduces this task to one simple sum command:
sum(1:2:str2double(s))

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Maneet Kaur Bagga
Ran in:
As per my uderstanding you want to create a loop which asks for an input from the user and returns the sum of odd numbers between 1 and the input number. Please find the code below as a solution. Hope it helps!
x = 100
x = 100
% You can use x = input() to take input from the user
num_sum = sum(1:2:x)
num_sum = 2500

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