Understanding Set R^R: Definition and Use in Function Analysis

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R^R refers to the set of all functions mapping real numbers to real numbers. It can also denote an R-fold Cartesian product of real numbers, representing tuples of real numbers. In function analysis, R^R is used to show that functions produce real solutions. Each element of R^R can be viewed as a vector with real numbers in each slot. Ultimately, R^R is commonly understood as a function from R to R in mathematical contexts.
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Homework Statement


What is the set R^R? Is it used to define functions and show that the function produces real solutions?


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The Attempt at a Solution

 
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X^Y usually denotes the set of functions from Y to X.

But I've also seen R^R denote an R-fold Cartesian product of R.
 
quasar987 said:
X^Y usually denotes the set of functions from Y to X.

But I've also seen R^R denote an R-fold Cartesian product of R.

Okay, in this question after it writes R^R it says "of all functions from R to R", so i think they just mean that solutions are real?
 
"solutions" is not the right word, but I get what you mean.
 
quasar987 said:
"solutions" is not the right word, but I get what you mean.

Oh sorry, i mean the function maps to a real number.
 
Formally, R^R is indeed the set of all R-fold tuples of real numbers. That is, an element of R^R is sort of a vector, containing in each slot a real number, and having as many slots as there are real numbers.
In everyday mathematical usage we call such an object a function from R to R.
 
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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