What is the Difference Between 'Identically Zero' and 'Zero' in Mathematics?

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Discussion Overview

The discussion revolves around the terminology used in mathematics regarding the phrases "identically zero" and "zero," particularly in the context of functions over specified intervals. Participants explore the implications of these terms and their usage in mathematical communication.

Discussion Character

  • Conceptual clarification, Technical explanation

Main Points Raised

  • One participant questions the necessity of the term "identically zero" compared to simply stating "zero," suggesting it may seem superfluous.
  • Another participant explains that saying "f is zero on the interval [a,b]" could imply there exists a point c in [a,b] where f(c) = 0, which could lead to misunderstandings. They argue that using "identically zero" clarifies that the function is zero for all points in the interval.
  • A third participant notes that "identically" can serve as an emphasis, providing the example of sin²θ + cos²θ being identically 1.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and clarity provided by the term "identically zero." There is no consensus on whether it is superfluous or essential for clear communication.

Contextual Notes

The discussion does not resolve the nuances of how "zero" and "identically zero" are interpreted in different mathematical contexts, nor does it clarify the implications of these terms in various applications.

member 428835
hey pf!

when would you use "identically zero" as opposed to simple "zero". example: f is identically zero on interval a to b. or, f is zero on interval a to b.

why do we ever use identically? it seems superfluous...

thanks!
 
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It's because the statement "##f## is zero on the interval ##[a,b]##", might be interpreted as there is a ##c\in [a,b]## such that ##f(c) = 0##. I know that the proper language should be that "##f## has a zero", rather than what I wrote. But writers want to be clear and write that it is identically zero to avoid misunderstandings.
 
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'Identically' is sometimes used for emphasis.

Of course, sin^{2}θ + cos^{2}θ is identically 1.
 
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thanks to you both!
 

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