# MATLAB/Cookbook/for and while loops

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For & While Loops

%Loops are meant for running an operation or program a multiple times to be effectively useful.

```
%for loop - runs for a specified period of cycles
num = input('how many times do you want this to run?')
%{variable 'num' is given a value by user input}
for k = 1:num
%k is a variable that allows loop to work, allows program to cycle what the programmer wants (2,3,4.... times)}
y(k) = 3*k + sqrt(k + 5)
%loop runs # times and # indexes & helps compute 'y'}{sqrt = square root}
end %'end' terminates the loop and stops execution}
%Each time the loop runs through the program, y(1) is computed, y(2) is computed......'k' is % given a new value each time a new loop starts
%while loop - runs until a specific condition is met
x = 0; %x needs to have an established starting value for a 'loop counter' to see how %many times it runs}
y = 0; %y needs to have an established starting value}
while y < 100 %conditional statement stating while 'y' is less than 100, keep running the program,
%once it equals/greater than 100-program stops
x = x + 1 %'x' serves as a 'loop counter'}
y = 2*x + 5 %simple math to get 'y' to desired condition}
end %end' terminates the loop and stops execution}
```