Farzad Bashtani

Im planning to solve the following problem with trial and error in c++ after solving this equation by calculating the partial derivatives and force them to be equal to ZERO we obtain the attached equations for a b c. as you can see we have to use the trial and error method to solve this problem for a b c the problem is the first guess of a b c. based on the first guess the answer changes and usually goes to infinity !!! Im asking you to help me to find the proper first guess. Ive attached a set of sample xi yi data to the post too. data_file.txt just in case I attach the c++ class I have programmed to this post too. PowerRegression.zip .

Hi in my previous topic we reached to a conclusion that I need to find the minimum value of the following function . [math] cost(a, b, c) = \Sigma_i (y_i - a x_i^b - c)^2 [/math] "yi" and "xi" are the result of a complicated analysis on my lab data and I need to find a,b,c in a way that COST(a,b,c) function be minimum. I know its simple to use mathematical softwares like matlab or mathematica. but I have to develop my program with c++ so I need to know the algorithm of this process. can you help me with that ? I would be appreciated

thanks a lot for your advise. now I know what I need to do. now the problem is the fminsearch function. Im using c++ for this project. so I need to write this function by myself. can you help me with the algorithm of this? how am I suppose to find this minimum value for the cost function? ---Im going to add a new topic on the forum for this issue

thanks for the advise there are two things I need to mention My function is Y=a*(x^b)+c . so it becomes Log (y-c) = Log a + b*Log x . about the value of c I still have no Idea how I can determine it ! I give you a sample of the data that I'm trying to fit with this curve. I would be appreciated for your advice K(t)_K(0)_OUTPUT.txt

I have a set of X and Y points and I want to fit a Power curve to them. Y = a*X^b + c whats the algorithm for determining a,b,c?