How to use a while loop to achieve the maximum value of a plot?

Hi guys, I'm having a hard time solving this particular problem;

Plot the function y=10(1-e^-x/4) using a while loop for the interval 0≤ x ≤ xmax, xmax should be the value of where y(xmax)=9.8.

I would appreciate some help!

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

Answer 1

[KALYAN ACHARJYA]

x=0;
y=0;
%% Flowing code just find the xmax where y<9.8
while y<9.8
    y=10*(1-exp(-x/4));
    x=x+0.1;
end
% The output of the above code is x, which is xmax
xmax=x;
%% Plot y, where x varies from 0 to xmax
x=0:.1:xmax;
y=10*(1-exp(-x/4));
plot(x,y);

Answer 2

[Walter Roberson]

x = 0;
yx = y(x);
while yx < 9.8
    x = x + randn();
    yx = y(x);
end

x is now an upper bound for xmax, and you have used a while loop in your calculation, so once you have done this, you can switch to more useful methods.