From: ammammata@tiscali.it   
      
   After serious thinking R.Wieser wrote :   
   > Can anyone tell me what goes wrong here ?   
      
   i pasted your post into chatgpt, it says:   
      
      
   You’re very close — the issue is a combo of log base, formula form, and   
   how Mercator Y is mapped to pixels. Nothing fundamentally wrong with   
   your trig. Let’s untangle it cleanly.   
      
   then it explains a possible error in your formula and suggests the   
   workaround   
      
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   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)