Talk:Sine quadrant

Navigation and Scale questions
Hi. In the article on the Rule of Marteloio, I have inserted a reference which claims there is a close resemblance between the Arab Sine quadrant and the Italian "tondo e quadro" used for navigation in the 15th C. Does anybody know if the Rubul mujayyab was used in the same fashion by Arab navigators? That is, to calculate trigonometric solutions to the traverse sailing problem (or what sort of trigonometric problems it would be applied to)? I am also a little confused by the scale of the Rubul mujayyab. While angular measurement is clearly described in the article, the role of the grid scale (i.e. how to use it to find solutions) is less clear. If anyone can help elucidate how it was used (e.g. with an example), it would be wonderful. Walrasiad (talk) 23:21, 22 August 2011 (UTC)

Jamaludheen maradeenis book on the rub ul mujaib
The book referenced by Gafoor Thottungul is still printed in India and is used to calculate the islamic prayer times. It describes in a step by step fashion(algorithm)how the trignometric calculations can be performed by the instrument.If wikipedia allows referencing such material I can explain how the qudrant was used by the arabs. — Preceding unsigned comment added by Ashraf a a (talk • contribs) 15:14, 3 November 2013 (UTC)