Determining coefficients from an equation with 3 variables

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Discussion Overview

The discussion revolves around solving an equation related to worm gear mechanics, specifically focusing on extracting coefficients from a complex equation involving three variables: ##l_1##, ##\theta_1##, and ##\phi_1(\phi_2)##. Participants explore the application of Cramer's Rule and the structure of the equation as presented in a referenced paper.

Discussion Character

  • Technical explanation, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant questions the validity of the expression, suggesting that ##\phi_1## is the only variable present in the equation.
  • Another participant echoes this concern, noting that they are also searching for any errata that might clarify the equation's structure.
  • A different participant proposes that there may be typos in the equation, suggesting that ##\gamma_1## could be equal to ##\theta_1## and that ##1## might represent ##l_1##.
  • The original poster expresses uncertainty about the notation and the potential loss of variables due to substitutions and expansions in the equation.
  • The original poster seeks guidance on how to extract coefficients for use with Cramer's Rule, questioning whether the equation truly represents a matrix system of linear equations.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the correctness of the expression or the presence of typos. Multiple competing views regarding the interpretation of the equation remain unresolved.

Contextual Notes

There are indications of missing assumptions and potential typographical errors in the equation as presented, which may affect the interpretation and application of Cramer's Rule.

RichardWattUK
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TL;DR
Determining coefficients from an equation with 3 variables
Hi,

Some of the background related to this question is in this thread, but I've got another question as I'm looking at another problem that has come up with the same application which I'm trying to solve using the equation of meshing for a worm gear and the cutting/grinding tool that creates it. This is taken from the paper "Contact Characteristics of Recess Action Worm Gear Drives With Double-Depth Teeth", which you can view here, specifically Equation 16:

$$f(l_1,\theta_1,\phi_1(\phi_2))=\omega_1{[(m_21 cos \gamma_1-1) Y_1+m_21(cos \phi_1 sin \gamma_1 Z_1 + sin \phi_1 cos \gamma_1 C_1)]N_x1+[-(m_21 sin \gamma_1-1) X_1+m_21(-sin \phi_1 sin \gamma_1 Z_1 + cos \phi_1 cos \gamma_1 C_1)]N_y1+[m_21 sin \gamma_1(-cos \phi_1 X_1 + sin \phi_1 Y_1 + C_1)]N_z1}=0$$

This has 3 variables in it - ##l_1##, ##\theta_1##, ##\phi_1(\phi_2)## - now, some of the notation is not familiar to me since it's been about 20 years since I last studied math(s), but I've found that I may be able to use Cramer's Rule to solve for the 3 variables if I can construct a 3x3 matrix of the coefficients and a 3x1 vector for the results.

What I also find strange is there's the ##f(l_1,\theta_1,\phi_1(\phi_2))## part but the main equation only references ##\theta_1##, but since this equation is created using other equations, that could cause the loss of ##l_1## and ##\theta_1## due to the substitutions and expansions I suppose?

So, how would I solve this equation, and how would I get the coefficients from it to use with Cramer's Rule? It looks to me like a matrix system of linear equations, but is it really?
 
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The expression doesn't look right. ##\phi_1## is the only variable there.
 
mathman said:
The expression doesn't look right. ##\phi_1## is the only variable there.
I was thinking the same thing, but that's how it's written in the paper and I've been looking for an errata in case there were any corrections made since but I can't find anything.
 
It looks there may be typos like ##\gamma_1=\theta_1?## and ##1=l_1?##.
 

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