Saturday, January 13, 2018

intuition - Numbers to the Power of Zero



I have been a witness to many a discussion about numbers to the power of zero, but I have never really been sold on any claims or explanations. This is a three part question, the parts are as follows...






1) Why does $n^{0}=1$ when $n\neq 0$? How does that get defined?



2) What is $0^{0}$? Is it undefined? If so, why does it not equal 1?




3) What is the equation that defines exponents? I can easily write a small program to do it (see below), but what about in equation format?






I just want a little discussion about numbers to the power of zero, for some clarification.






Code for Exponents: (pseudo-code/Ruby)




def int find_exp (int x, int n){
int total = 1;
n.times{total*=x}
return total;
}

Answer



It's basically just a matter of what you define the notation to mean. You can define things to mean whatever you want -- except that if you choose a definition that leads to different results than everyone else's definitions give, then you're responsible for any confusion brought about by your using a familiar notation to mean something nonstandard.



Most commonly we define $x^0$ to mean $1$ for any $x$. What you find in discussions elsewhere are argument that this is a useful definition, not arguments that it is correct. (Definitions are correct because we choose them, not for any other reason. That's why they are definitions).




Some people choose (for certain purposes) to explicitly refrain from defining $0^0$ to mean anything. That choice is (supposedly) useful because then the map $x,y\mapsto x^y$ is continuous in the entire subset of $\mathbb R\times\mathbb R$ it is defined on. But it's an equally valid choice to define $0^0$ to mean $1$ and then just remember that $x,y\mapsto x^y$ is not continuous at $(0,0)$.


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