To find value of variable using iteration

Hello,

At first I need to generate a random number that was done using rand command.

Then I have to use iteration such that it satisfies a certain relation. I used while loop but it is not stopping.

x = rand(1,1);

while 350-12.9-x-32.4498 ~= 0

x= x+ 0.0001

end

The problem is other values can also change drastically so it would take a long time to find values. Any other suggestions?

Answer 1

[Image Analyst]

Your condition never matches 0 exactly. Why not? See the FAQ:

https://matlab.fandom.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

Try it like this:

x = rand(1,1);
maxIterations = 10000000; % Failsafe to prevent infinite loop
loopCounter = 0; % Failsafe to prevent infinite loop
value = abs(350-12.9-x-32.4498);
while value >= 0.00009 && (loopCounter < maxIterations)
    x = x + 0.0001;
	value = abs(350-12.9-x-32.4498);
    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);

You might get:

After 3038399 iterations, x = 304.650168 and value = 0.000032.

[Dhananjay Singh]

does rand function only generate number less than 1?

[Image Analyst]

Yes, only between 0 and 1. See the help if you need it in a range different from that

r = vMin + (vMax - vMin) * rand(1); % Get value between vMin and vMax

Answer 2

[Awais Saeed]

What is your goal exactly? Do you want to find the value for x where the result is zero? You can find the roots using solve

syms x
vpa(solve(350-12.9-x-32.4498 == 0,x))

ans = 

304.65019999999999669171302230097

[Dhananjay Singh]

x = .. some guess number

y = f(x);

z= f(y);

w=g(y);

a=z+x+w;

x is to be guessed first ,then using relations find y,z,w and a is a constant value such that the relation satisfies.

was thinking of iteration of doing this . Is there any other method?