On 2/3/20 10:28 AM, Csaba Láng wrote: > Back to the difference of Iohannes' suggestions, looks like [expr atan...] > gives results only from -90 to 90 degrees, [atan2] gives from -180 to 180.
yes, quite obviously. this is why atan2 was introduced (in various programming languages; Pd is only following other implementations, like C). the problem being that you cannot distinguish -1/-1 from 1/1 (both will yield the same result; however, for the atan the signs of the numerator & denominator determine the quadrant of the output. > And the atan2 is 90 degree rotated: atan2 results 0 degree on (1;0) while > the expression gives 0 degrees on (0;1) and (0;-1). dunno what you mean. [atan2] and [expr atan2($f1,$f2)] give exactly the same results. (of course if you use [expr atan2($f2,$f1)] you reverse the arguments; but that's what you ask for...) gfmdsar IOhannes
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