The notation of the norm of polynomials

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The discussion centers on confusion regarding the notation of polynomial norms, particularly the meaning of x_i. Participants clarify that x_i refers to the ith dimension of x, rather than the coefficient of x. There is also a comparison made to a different source, highlighting variations in notation. The main expression discussed involves the square root of the sum of squared differences between x_i and its square. Overall, the conversation seeks to clarify the interpretation of polynomial norm notation.
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what is x_i? is it the coefficient of x or simply add up 1-5?
i found the notation different from http://mathworld.wolfram.com/PolynomialNorm.html
so i am confused. Thx!
 

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Basically, that middle part is equivalent to saying:

\sqrt{(x_1-x_1^2)^2 + (x_2-x_2^2)^2 + (x_3-x_3^2)^2 + (x_4-x_4^2)^2 + (x_5-x_5^2)^2}

Is that what you were asking?
 
Char. Limit said:
Basically, that middle part is equivalent to saying:

\sqrt{(x_1-x_1^2)^2 + (x_2-x_2^2)^2 + (x_3-x_3^2)^2 + (x_4-x_4^2)^2 + (x_5-x_5^2)^2}

Is that what you were asking?

sorry, i know the notation. But i don't know what x_i means? coefficient of x?
 
No, it actually means the ith dimension of x, I believe.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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