From:	"Damian Yerrick" <NOSP AT Msnews@pineight.8m.com>
Newsgroups:	comp.os.msdos.djgpp
References:	<wKza4.591$eq DOT 7079 AT uutiset DOT nic DOT fi>
Subject:	Re: Inverse trigonometry functions in Djgpp
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NNTP-Posting-Date:	Thu, 30 Dec 1999 05:51:48 GMT
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Date:	Thu, 30 Dec 1999 05:51:48 GMT
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"Jarkko Kähkönen" <jarkko DOT kahkonen AT mbnet DOT fi> wrote in message
news:wKza4.591$eq DOT 7079 AT uutiset DOT nic DOT fi...
> Atan () - don't work!
> Here is a bit of my code:
>
> float direction;
>
> direction = atan ( 120 / 90 );
> printf ("%f", direction");
>
> And output is this:
> 0.927-something
>
> But with calculator it is:
> tan^-1 (120 / 90) = 53.13-something
>
> Is atan () right inverse tan function?

Yes. Ever heard of something called a radian?
Try putting your little calculator into "radian" mode
(push DRG for drugs?) and try your arctan again.

Basically, there are 2*Pi (about 6.283) radians in a circle
instead of 360 degrees. Multiply atan's "radian" output by
57.29578 to get degrees.

--
Damian Yerrick    http://yerricde.tripod.com/
View full .sig:  http://www.rose-hulman.edu/~yerricde/sig.html










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