Question about Sawtoothwave Function

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Homework Help Overview

The discussion revolves around the properties of a sawtooth wave function, particularly its periodic nature and the implications of including endpoints in the defined intervals. Participants explore the behavior of the function at specific points, especially at the boundaries of the intervals.

Discussion Character

  • Conceptual clarification, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants question why the endpoint 'a+P' is excluded from the interval and what implications this has for the function's value at that point. There are discussions about the periodicity of the function and the values at specific points like f(1) and f(0).

Discussion Status

Multiple interpretations of the function's behavior at the boundaries are being explored. Some participants suggest that including the endpoint could lead to conflicting definitions of the function, while others express confusion about the graphical representation versus the mathematical definition.

Contextual Notes

There is an ongoing debate about the definition of the function at the boundary points and the implications of periodicity. Participants reference textbook definitions and graphical representations, indicating a potential discrepancy between the two.

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Homework Statement



For a sawtooth wave function with a period of P where the first branch of the function is given for [a, a+P) we can say that :

f(x)=some expression in x for [a, a+P)

f(x+nP)=f(x)

Homework Equations


The Attempt at a Solution



Why is 'a+P' not included in the x-interval? Wouldn't f(x) equal 1 if x was 1? What would happen if 'a+P' was included in the interval?

Thank You.
 
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We have that f(a+P)=f(a). So knowing the value of f(a) means that we also know the value of f(a+P). So there is no need to include a+P.
 
micromass said:
We have that f(a+P)=f(a). So knowing the value of f(a) means that we also know the value of f(a+P). So there is no need to include a+P.

The graph in my textbook has a straight line branch between x=0 and x=1 that repeats itself indefinitely. The highest Y equals 1. For [0,1) the output from f is given as f(x)=x.

So if x is 0.5 then f(x) is 0.5. What is f(x) if x=1?
 
If f(0) = 0, and the function is periodic with period 1, then f(1) = 0 also.
 
SammyS said:
If f(0) = 0, and the function is periodic with period 1, then f(1) = 0 also.

From the book:

"f(x+1)=f(x) for [0,1)

For example, f(1.5)=f(0.5+1)=f(0.5)=0.5"

Period here is 1. y=1 when x=1 on the graph. Does it mean that x=1 is undefined or something?
 
f(1)=f(0)=0.
 
solve said:
From the book:

"f(x+1)=f(x) for [0,1)

For example, f(1.5)=f(0.5+1)=f(0.5)=0.5"

Period here is 1. y=1 when x=1 on the graph. Does it mean that x=1 is undefined or something?
It may look like y=1 when x=1, however y only gets very close to 1 when x gets very close to 1.

f(0.999995) = 0.999995 , f(0.99999999993) = 0.99999999993 , f(1) = 0
 
micromass said:
f(1)=f(0)=0.

f(1)=0 if you go by definition, f(1)=1 if you go by the picture of the graph. Too confusing.
 
SammyS said:
It may look like y=1 when x=1, however y only gets very close to 1 when x gets very close to 1.

f(0.999995) = 0.999995 , f(0.99999999993) = 0.99999999993 , f(1) = 0

So what would happen if I were to include 1 in the interval?
 
  • #10
solve said:
f(1)=0 if you go by definition, f(1)=1 if you go by the picture of the graph. Too confusing.

The picture of the graph is wrong. On several points. For example, that line straight down doesn't happen, you just have a discontinuity


solve said:
So what would happen if I were to include 1 in the interval?

You can't. If you include 1, then f(1) would have multiple definitions, this is not good.
 

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