Odd/even functions and periodicity

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In summary, the conversation discusses a theorem stating that if a function is odd and another function related to it is even, then the original function is periodic with a maximum period of 4t. The speaker also asks if there are other similar theorems and mentions their failure to find more results. They provide a specific example with the function f(x)=sin(x) and explain their approach using definitions and values such as t=pi/2 and n=4. The current result is that f(n2t)=0 for all integer n, indicating that f(x) is periodic with a maximum period of 4t.
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dimitri151
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You can prove if f(x) is an odd function and f(x+ t) is an even function then f(x) is periodic with period at most 4t. Are there other theorems like that?i know this is a somewhat open ended and general question, it's just i would like to squeeze some more results from this angle and can not.
 
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i would like to squeeze some more results from this angle and can not.
... what "more results"? "more" suggests you have already got some results. What results have you got so far?

Consider the specific example where f(x)=sin(x).
The general approach would start with the definitions of both.

(modify slightly so that f(x-t) is even, makes it easier to write...)

if f(-x)=-f(x) and f(t-x)=f(x-t) then f(x)=f(x-nt): n in Z (?)

for f(x)=sin(x), t=pi/2, n=4.
 
  • #3
The result so far is that if f(x) is odd and f(x+t) is even then f(n2t) =0 for all integer n, f(x) is periodic, and the minimum period is no greater than 4t.
 

1. What is an odd function?

An odd function is a mathematical function where f(-x) = -f(x). In other words, when you replace x with its negative counterpart, the function outputs the negative of its original value. Graphically, this means that the function is symmetric about the origin.

2. What is an even function?

An even function is a mathematical function where f(-x) = f(x). This means that when you replace x with its negative counterpart, the function outputs the same value as its original input. Graphically, this means that the function is symmetric about the y-axis.

3. How do you determine if a function is odd or even?

To determine if a function is odd or even, you can use the properties mentioned in the previous questions. If f(-x) = -f(x), then the function is odd. If f(-x) = f(x), then the function is even. You can also look at the graph of the function and see if it exhibits the appropriate symmetry.

4. What is periodicity in a function?

Periodicity in a function means that the function repeats itself at regular intervals. This means that after a certain value of x, the function will start to repeat its output values. This can be seen in trigonometric functions, where the sine and cosine functions have a period of 2π.

5. Can a function be both odd and even?

No, a function cannot be both odd and even. This is because the properties of odd and even functions are mutually exclusive. If a function is odd, it means that it is symmetric about the origin. If it is even, it means that it is symmetric about the y-axis. These two types of symmetry cannot coexist in the same function.

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