Talk:Ibn Sahl (mathematician)

Nationality
Ibn Sahl seems to have been Persian. Some versions say he was an Arab. — Preceding unsigned comment added by 93.97.194.200 (talk) 14:20, 11 November 2011 (UTC)
 * See the remarks in the Talk page of the German article on Ibn Sahl. — Preceding unsigned comment added by 93.97.194.200 (talk) 12:05, 15 November 2011 (UTC)

Puzzling sentence
The article contains the following sentence: "According to Roshdi Rashed,[3] an author and historian of medieval science and mathematics, the ratio of the length of the smaller hypotenuse to the larger is the reciprocal of the refractive index of the crystal." I am somewhat puzzled by this.

What is stated is a straightforward consequence of Snell's law. Deriving it needs only the most elementary trigonometry. There is no need for a medieval science scholar for this. One could write: "It is straightforward to demonstrate that, according to Snell's law, the ratio of the larger hypotenuse to the smaller is thee refractive index of the crystal." True, but in itself not interesting. I guess the intention of the sentence is to show how Ibn Sahl expressed the law of refraction, and that what he wrote is equivalent to the sine law. But surely Ibn Sahl did not talk about the refractive index of a crystal.

Can somebody clarify this?

Karloman2 (talk) 09:14, 12 April 2014 (UTC)
 * You are not the only one who is puzzled by the article by Roshdi Rashed. See the discussion on the Talk page of Snell's law, see Talk-section Talk:Snell's law#Elaborate_on_Ibn_Sahl.27s_authorship_of_the_law--Gerard1453 (talk) 15:58, 25 October 2017 (UTC)