math domain error while using PCA

Question

I am using python\'s scikit-learn package to implement PCA .I am getting math

domain error :
C:\\Users\\Akshenndra\\Anaconda2\\lib\\site-packages\\sklearn\\deco         


        

Answer 1

I don't know whether i am right or not, but I truly find a way to solve it.

I just print some error information(The value of spectrum_[i] and spectrum_[j]), and I find :

sometimes, they are same!!!

(Maybe they are not same but they are too close, I guess)

so , here

pa += log((spectrum[i] - spectrum[j]) *
                  (1. / spectrum_[j] - 1. / spectrum_[i])) + log(n_samples)

it will report error when calculate log(0).

My way to solve it is to add a very small number 1e-99 to 0, so it become log(0 + 1e-99)

so you can just change it to:

            pa += log((spectrum[i] - spectrum[j]) *
                  (1. / spectrum_[j] - 1. / spectrum_[i]) + 1e-99) + log(n_samples)