nasaconstellation.com.arctan2(x1, x2, /, out=None, *, where=True, casting="same_kind", order="K", dtype=None, subok=True<, signature, extobj>) = "arctan2">

Element-wise arc tangent of x1/x2 choosing the quadrant correctly.

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The quadrant (i.e., branch) is chosen so that arctan2(x1, x2) isthe signed angle in radians between the ray ending at the origin andpassing through the point (1,0), & the ray ending at the origin andpassing through the point (x2, x1). (Note the role reversal: the“y-coordinate” is the first function parameter, the “x-coordinate”is the second.) By IEEE convention, this function is defined forx2 = +/-0 và for either or both of x1x2 = +/-inf (seeNotes for specific values).

This function is not defined for complex-valued arguments; for theso-called argument of complex values, use angle.

Parametersx1array_like, real-valued

y-coordinates.

x2array_like, real-valued

x-coordinates.If x1.shape != x2.shape, they must be broadcastable lớn a commonshape (which becomes the shape of the output).

outndarray, None, or tuple of ndarray và None, optional

A location into which the result is stored. If provided, it must havea shape that the inputs broadcast to. If not provided or None,a freshly-allocated array is returned. A tuple (possible only as akeyword argument) must have length equal lớn the number of outputs.

wherearray_like, optional

This condition is broadcast over the input. At locations where thecondition is True, the out array will be set to the ufunc result.Elsewhere, the out array will retain its original value.Note that if an uninitialized out array is created via the defaultout=None, locations within it where the condition is False willremain uninitialized.

**kwargs

For other keyword-only arguments, see theufunc docs.

Returnsanglendarray

Array of angles in radians, in the range <-pi, pi>.This is a scalar if both x1 and x2 are scalars.

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arctan, tan, angle

Notes

arctan2 is identical lớn the atan2 function of the underlyingC library. The following special values are defined in the Cstandard: <1>

x1

x2

arctan2(x1,x2)

+/- 0

+0

+/- 0

+/- 0

-0

+/- pi

> 0

+/-inf

+0 / +pi

Note that +0 và -0 are distinct floating point numbers, as are +infand -inf.

References

1

ISO/IEC standard 9899:1999, “Programming language C.”

Examples

Consider four points in different quadrants:

Note the order of the parameters. Arctan2 is defined also when x2 = 0and at several other special points, obtaining values inthe range <-pi, pi>: