What should we call the type of dervative that isn't a partial derivative?

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Discussion Overview

The discussion revolves around the terminology used to describe derivatives that are not partial derivatives, specifically whether terms like "perfect derivative," "ordinary derivative," or "total derivative" are appropriate. The scope includes conceptual clarification and terminology in calculus.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that the partial derivative of a function g with respect to y is equivalent to what they term the "perfect derivative" of another function f, questioning the standard terminology.
  • Another participant simply refers to it as the "derivative," indicating a lack of advanced calculus experience.
  • A different participant argues that the partial derivative of g with respect to y should not be given a new name just because it coincides with the partial derivative of f with respect to x, emphasizing that it is simply a partial derivative.
  • One participant states that in English, the term "ordinary" derivative is used to distinguish it from partial derivatives, similar to the distinction made in differential equations.
  • Another participant agrees that "ordinary" derivative is a common term and adds that "total" derivative is also used, associating it with the concept of exact derivatives in functions of several variables.
  • Another participant reiterates the term "total" derivative and connects it to the idea of exact derivatives, noting that for functions of one variable, the terms may be interchangeable.

Areas of Agreement / Disagreement

Participants express differing views on the appropriate terminology for derivatives that are not partial derivatives, with no consensus reached on a single term. Some propose "ordinary" or "total" derivatives, while others challenge the need for new terminology.

Contextual Notes

There are unresolved assumptions regarding the definitions and contexts in which these terms are applied, particularly concerning the distinction between ordinary and total derivatives in various mathematical settings.

cmos
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For example, let f and g be defined as
[tex]f=x^2[/tex]
[tex]g=2xy[/tex]

I would say that the partial derivative of g with respect to y equals the perfect derivative of f(x). I've never been convinced that this is standard (or even correct) terminology. I am curious what some of you would use in place of perfect derivative.
 
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I thought it was just called the derivative :P. Then again I haven't taken anything beyond elementary calculus so I can't really say.
 
Huh? The partial derivative of g wrt to y is just that. Just because the partial derivative of g wrt to y happens to be same as the partial derivative of f wrt x doesn't mean anything unless it's part of a certain class of DE problems. Why give it a new name?
 
In English, at least, that is called an "ordinary" derivative just as "ordinary" differential equations are distinguished form "partial" differential equations.

There is the concept of "exact" differentials in functions of several variables but that is a different matter. A differential f(x,y)dx+ g(x,y)dy is "exact" if and only if there exist a function, F(x,y), such that dF= f(x,y)dx+ g(x,y)dy.
 
HallsofIvy said:
In English, at least, that is called an "ordinary" derivative just as "ordinary" differential equations are distinguished form "partial" differential equations.
I have heard it called a "total" derivative also.
 
DaleSpam said:
I have heard it called a "total" derivative also.

I would associate "total" derivative with "exact" derivative of a function of several variables. Of course, if we are talking about a function of one variable, they are all the same.
 

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