[metapost] Metafun : is "atan" the arctangent function?
franck.pastor at me.com
Sun Jan 12 12:28:05 CET 2014
Reading the "Metafun manual" (2010 edition), I noticed that it mentions p. 324 the existence of a specific "atan" unary operator. I assumed it was the arctangent function and I was pleasantly surprised, since this important inverse trigonometric function was not referenced in chapter 9 ("Functions") of the same Metafun manual. So I gave this atan operator a try but it returned me surprising results. For example, this short line
gives me "0.7282" as result ("0.7238095238095239" with numbersystem set to "double"), whereas the right result should be something like "0.7854" in radians (approximation of the exact result, pi/4) and exactly "45" in degrees.
Is "atan" thus actually meant as the arctangent function, of something else? Or is it a bug?
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