Prevention of negative value in Iteration

What to change here such that final value never goes negative i.e (0<value<=0.00009) and x changes accordingly

x = 0.77;
maxIterations = 10000000; % Failsafe to prevent infinite loop
loopCounter = 0; % Failsafe to prevent infinite loop
value = (0.5-x);
while value >= 0.00009 && (loopCounter < maxIterations)
    x = x + 0.0001;
	value = (0.5-x);
    loopCounter = loopCounter + 1; % Failsafe to prevent infinite loop
% 	fprintf('After %d iterations, x = %f and value = %f.\n', loopCounter, x, value);
end
fprintf('After %d iterations, x = %f and value = %f.\n', loopCounter, x, value);

After 0 iterations, x = 0.770000 and value = -0.270000.

Answer 1

[Walter Roberson]

while value >= 0.00009 && (loopCounter < maxIterations)
    newx = x + 0.0001;
	newvalue = (0.5-newx);
    if newvalue < 0.00009; break; end
    x = newx;
    value = newvalue;
    loopCounter = loopCounter + 1; % Failsafe to prevent infinite loop
% 	fprintf('After %d iterations, x = %f and value = %f.\n', loopCounter, x, value);
end

[Dhananjay Singh]

The value of 'value ' is still coming negative

[Walter Roberson]

You define

x = 0.77;
value = (0.5-x);

but 0.5 is less than 0.77, so your very first value is negative. There is no "previous" value to stop at.

Your initial x is too large for your initial value

[Dhananjay Singh]

that's what i am looking to find a value of x by iteration such that value is not negative and value is nearly equal to 0.

[Walter Roberson]

I suggest you use fzero() or fsolve()