POV-Ray : Newsgroups : povray.newusers : Calculation errors : Calculation errors Server Time
18 May 2024 07:54:41 EDT (-0400)
  Calculation errors  
From: kurtz le pirate
Date: 14 Sep 2023 11:23:06
Message: <6503255a$1@news.povray.org>
Hello,

I'm trying to adapt an Excel spreadsheet in POV. I've got a strange problem.

In Excel
Cell E19 = 280.8191102;
Cell E20 = 23.43825611;
Cell E21 = DEGRES ( ATAN2 ( COS(RADIANS(E19));
COS(RADIANS(E20))*SIN(RADIANS(E19) ) ) )

E21 = -78.23396726


In POV
#declare E19 = 280.8191102;
#declare E20 = 23.43825611;
#declare RESULT =degrees(atan2(cos(radians(E19)),
cos(radians(E20))*sin(radians(E19))));

RESULT = 168.233967


No obvious relationship between this -78.2 and +168.2
How to explain this difference ?

Especially since the correct value is -78.2 or 281.7 !
(Note that the numbers after the decimal point are exactly the same.)

Are the origins of angles and rotation direction in Excel and POV
different ?

help apprecied

-- 
Kurtz le pirate
Compagnie de la Banquise


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