Now letвЂ™s take a look at implementing this example problem in MATLAB. This time when we evaluate our logical expression our current value of x is actually greater than 20 so this statement is false and our while loop ends.

Our new value for x now has a value of 41. Now we evaluate our statement our new value of x is equal to 3 times the old value of x minus 1. This logical expression is true and we begin our third loop pass. We return to our logical expression and it is still true our current value of x which is 14 is less than 20. This statement is true and we evaluate our statement again our new value of xis equal to three times our current value of x minus one and our new value of x is now 14. We will continue to complete loop passes so our current value of x is 5 that is less than 20. Next, we return to our logical expression, and while this statement is true. Our new value of x is assigned the value of 3 times our current value of x minus 1 and our new value of x is now 5. Now letвЂ™s take a look at a flowchart of this example to demonstrate each loop pass.ДЇirst, we initialize our variable x which is assigned the value of 2 and we evaluate our logical expression our current value of x is 2 that is less than 20 that statement is true and we begin our first loop pass by evaluating the statement. So for example if x was always equal to 2 then it would also always be less than 20 and this loop would run infinitely.

So in this case our loop variable is x and it must be changed if it is not we would run into an infinite loop. The second note I would like to make is this the variable must be changed by the statements. Now I would like to make two important notes here when working with while loops first the loop variable must have avalue before the while statement in our case we have assign x = 2 if we did not initialize the variable x then we would have nothing to compare to in this logical expression so for example if there was no x then you could not evaluate the logical expression is x less than20. In this case we start by initializing a variable x which has a value of 2 and while x is less than 20 the statements are evaluated which in this case the new value of x is assigned the value of 3 times the current value of x minus 1.

For loops matlab