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atan2
The four-quadrant inverse tangent function
(p)=atan2(y,x)
(p)=atan2(y,x,deg)

Inputs
`x`	A real array. The arary of`y`-coordinates of points.
`b`	A real array of the same size as `a` .The array of `x`-coordinates of points.
`deg`	Optional input.
Outputs
`p`	A real array of the same size as `a` .

Description
For each pair (yi,xi) of elements of (y,x) , the corresponding element of the output p is the angle between the x-axis and the vector pointing from the origin to the point (xi,yi). If the optional argument deg is given any value , the angles are returned in degrees ; otherwise the angles are in radians.

Example

>>atan2(2,0,1)
              90
>>atan2(2,2)
          0.7854
>>atan2(2,-2,1)
             135
>>atan2(-2,2,1)
             -45
>>atan2(-1,0,1)
             -90