User talk:Cirdecle

Welcome!
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Happy editing! --Kmhkmh (talk) 11:27, 24 January 2024 (UTC)

Ellipse and Hyperbola
Hi @Cirdecle, and welcome to Wikipedia. Thanks for trying to fix what you thought were mistakes at Ellipse and Hyperbola. Please do make corrections where you find mistakes. However, also try to carefully double-check to make sure you aren't introducing an error. In this case the previous formulas were correct and your modified versions were not. You might be using different conventions than these articles e.g. for the definition of eccentricity, or you might have just made a mistake. One good way to check this kind of thing is to try plotting it in Desmos: https://www.desmos.com/calculator/3wddjec7ay. All the best. –jacobolus (t) 16:14, 24 January 2024 (UTC)


 * Hi @Jacobolus, for the case of hyperbola, $r=\frac{p}{e_{c}\cos\varphi-1}$ and $r=\frac{p}{-e_{c}\cos\varphi-1}$  are valid expressions as well. For the case of Ellipse, you're right in pointing out that there's a difference in the use of convention for the definition of eccentricity.  Cirdecle (talk) 02:08, 25 January 2024 (UTC)
 * Okay, fair enough, you're right you could write it that way. What would be the point of flipping the sign on the $r$ though? Since your edit summary was not accurate (in claiming the previous version drew the wrong thing), I didn't think too hard about whether the changed version was drawing the same curve, and I somewhat confused the change with the ellipse version, thinking you'd again swapped the $e$ and $1$. –jacobolus (t) 04:10, 25 January 2024 (UTC)
 * The reason I was brought to these 2 equations (instead of what you have) is from an engineering source on sketching the profile of lenses. It's just which side of the curve you begin plotting when your angle starts counting from \theta = 0. Anyway, appreciate your clarifications and corrections. Thanks. Cirdecle (talk) 04:43, 25 January 2024 (UTC)
 * Cheers. All the best, and again welcome! –jacobolus (t) 05:10, 25 January 2024 (UTC)