Hi John,
If I understand your point, I think that the confusion comes from the fact that for gnomonist the origin of azimuth is South , and not North like it is for navigators ( salesmen , pilots ). In such case East is -90°, West is +90°, North is +/- 180°. With this origin ( South = 0°), there is a symetry in the trigonometric circle : sin (pi - A) = sin A. As an example sin 120° = sin 60° = 0,866... For the same sine value, you have 2 angles. This is why you need to determine whether Az is > 90° or < 90° I hope that it answers your point. Best regards Hervé Guillemet ----- Mail original ----- De: "John Goodman via sundial " < sundial @uni-koeln.de> À: " Sundial List " < sundial @uni-koeln.de> Envoyé: Jeudi 11 Juillet 2024 20:03:10 Objet: Azimuth and altitude Diese Nachricht wurde eingewickelt um DMARC -kompatibel zu sein. Die eigentliche Nachricht steht dadurch in einem Anhang . This message was wrapped to be DMARC compliant . The actual message text is therefore in an attachment . --------------------------------------------------- https :// lists .uni-koeln.de/ mailman / listinfo / sundial
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