238338
Then , one computes the vector c = U ^ + ( x _ - x_k ) where U ^ + denotes the Moore – Penrose pseudoinverse of U. The number 1 is then appended to the end of c , and the extrapolated limit is where X = ( x_2 , x_3 , ... , x _ ) is the matrix whose columns are the k iterates starting at 2 .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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