Find dF/ds in Terms of u, v & w - Conditions and Assumptions

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Discussion Overview

The discussion revolves around finding the derivative dF/ds in terms of the variables u, v, and w, where s is a function of these variables. Participants explore the conditions and assumptions necessary for this transition, focusing on the implications of differentiating a smooth function F with respect to another smooth function s.

Discussion Character

  • Mathematical reasoning
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants note that dF/ds must be differentiated in a specific direction, indicating that different directions yield different derivatives.
  • It is proposed that all directional derivatives can be expressed in terms of the derivatives with respect to u, v, and w, which is a foundational aspect of multivariate calculus.
  • Participants emphasize that F is a smooth function, differentiable in any direction for u, v, and w.
  • There is a suggestion that dF/ds may relate to the sum of the derivatives dF/du, dF/dv, and dF/dw, but it is clarified that it is not equal to this sum.
  • One participant raises the idea that u, v, and w could be functions of the parameter s, which may influence the differentiation process.

Areas of Agreement / Disagreement

Participants express a general agreement on the smoothness of the functions involved and the need for directional differentiation. However, there is no consensus on the exact relationship between dF/ds and the derivatives with respect to u, v, and w, indicating ongoing exploration and uncertainty in the discussion.

Contextual Notes

Participants have not fully defined the assumptions regarding the relationships between s, u, v, and w, nor have they resolved the mathematical steps necessary to express dF/ds in the desired terms.

gomunkul51
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Hi!

As a part of a mathematical construction I used the rate of change of F(s) with s, i.e. dF/ds. F and s are smooth functions. The problem is that s(u,v,w) is a function of u, v & w and actually I need to find the rate of change of F with respect to u, v & w. The question is: what does dF/ds equals to in terms of u, v & w ?

Thank you in advance !

** Please also provide the conditions and assumptions for the transition.
 
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gomunkul51 said:
Hi!

As a part of a mathematical construction I used the rate of change of F(s) with s, i.e. dF/ds. F and s are smooth functions. The problem is that s(u,v,w) is a function of u, v & w and actually I need to find the rate of change of F with respect to u, v & w. The question is: what does dF/ds equals to in terms of u, v & w ?

Thank you in advance !

** Please also provide the conditions and assumptions for the transition.

In this case F must be differentiated in a direction. Different directions will give different derivatives. All of the directional derivatives can be expressed in terms of derivatives in the directions of u,v, and w. This remarkable fact makes multivariate calculus possible.
 
lavinia said:
In this case F must be differentiated in a direction. Different directions will give different derivatives. All of the directional derivatives can be expressed in terms of derivatives in the directions of u,v, and w. This remarkable fact makes multivariate calculus possible.

F is smooth, i.e. differentiable any number of times in any direction for u,v, and w.
s is a known smooth function of u,v, and w. I need dF/ds in terms that include u,v, and w.

Can you tell me then how do I construct it?

It is probably related to dF/du + dF/dv + dF/dw but not equal to it.
 
gomunkul51 said:
F is smooth, i.e. differentiable any number of times in any direction for u,v, and w.
s is a known smooth function of u,v, and w. I need dF/ds in terms that include u,v, and w.

Can you tell me then how do I construct it?

It is probably related to dF/du + dF/dv + dF/dw but not equal to it.

I think u,v,and w are functions of the parameter,s,
 

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