Section: Mathematical Functions
atan2 function for its argument.  The general
syntax for its use is
z = atan2(y,x)
where x and y are n-dimensional arrays of numerical type.
Integer types are promoted to the double type prior to
calculation of the atan2 function. The size of the output depends
on the size of x and y.  If x is a scalar, then z
is the same size as y, and if y is a scalar, then z
is the same size as x.  The type of the output is equal to the type of
|y/x|.  
-pi and pi.  The signs of x and y
are used to find the correct quadrant for the solution.  For complex
arguments, the two-argument arctangent is computed via
 
For real valued arguments x,y, the function is computed directly using 
the standard C library's numerical atan2 function. For both 
real and complex arguments x, note that generally
 
due to the periodicities of  cos(x) and sin(x).
atan2 
function and the atan function over the range [-pi,pi].
--> x = linspace(-pi,pi); --> sx = sin(x); cx = cos(x); --> plot(x,atan(sx./cx),x,atan2(sx,cx))
 
Note how the two-argument atan2 function (green line) 
correctly ``unwraps'' the phase of the angle, while the atan 
function (red line) wraps the angle to the interval [-\pi/2,\pi/2].