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Section: Mathematical Functions
Computes the cos function for its argument. The general syntax for its use is 
y = cos(x)
 where x is an n-dimensional array of numerical type. Integer types are promoted to the double type prior to calculation of the cos 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 cos function is defined for all real valued arguments x by the infinite summation 
![\[ \cos x \equiv \sum_{n=0}^{\infty} \frac{(-1)^n x^{2n}}{(2n)!}. \]](form_60.png) 
 For complex valued arguments z, the cosine is computed via 
![\[ \cos z \equiv \cos \Re z \cosh \Im z - \sin \Re z \sinh \Im z. \]](form_61.png) 
The following piece of code plots the real-valued cos(2 pi x) function over one period of [0,1]:
--> x = linspace(0,1); --> plot(x,cos(2*pi*x))
