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Section: Mathematical Functions
Computes the atan function for its argument. The general syntax for its use is 
y = atan(x)
 where x is an n-dimensional array of numerical type. Integer types are promoted to the double type prior to calculation of the atan function. Output y is of the same size and type as the input x, (unless x is an integer, in which case y is a double type). 
Mathematically, the atan function is defined for all arguments x as 
![\[ \mathrm{atan} x \equiv \frac{i}{2}\left(\log(1-i x) - \log(i x + 1)\right). \]](form_53.png) 
 For real valued variables x, the function is computed directly using the standard C library's numerical atan function. For both real and complex arguments x, note that generally
![\[ \mathrm{atan}(\tan(x)) \neq x, \]](form_54.png) 
 due to the periodicity of tan(x). 
The following code demonstates the atan function over the range [-1,1].
--> t = linspace(-1,1); --> plot(t,atan(t))
