Solving a equation for the X value with the given Y value

Hi all,

I have a function like this "y = @(x) (x./E) + (x./K).^(1/n);" with E = 209000, K = 1230, n = 0.1610 respectively. Basically, it is a Ramberg-Osgood equation. How can I solve it with the input of y = [0:0.0006:0.006] for x value?

Thanks in advance.

Kon

[madhan ravi]

y(0:0.0006:0.006) %?

[Yat Sheng Kong]

Hi ravi,

Thanks for your comment. Then I get a very small value like "0 2.87081339712919e-09 5.74162679425837e-09 8.61244019138756e-09 1.14832535885167e-08 1.43540669856459e-08 1.72248803827751e-08 2.00956937799043e-08 2.29665071770335e-08 2.58373205741627e-08 2.87081339712919e-08" in which I think it used this "y(0:0.0006:0.006)" as x-value for y output. What I try to obtain is the opposite way. The value of input of 0.0006, the output should be around 122.7.

Answer 1

[madhan ravi]

Result=zeros(numel(y),1);
for k=2:numel(y)
Result(k)=fzero(@(x)(x./E) + (x./K).^(1/n)-y(k),100*k);
end

[Yat Sheng Kong]

Thanks for this and I really appreciated it. By the way, can I know how to determine the initial value x0?

[madhan ravi]

It’s just a guess, plot using fplot() to get an idea.