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Subsections

COS Trigonometric Cosine Function

Usage

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).

Function Internals

Mathematically, the cos function is defined for all real valued arguments x by the infinite summation

$\displaystyle \cos x \equiv \sum_{n=0}^{\infty} \frac{(-1)^n x^{2n}}{(2n)!}.
$

For complex valued arguments z, the cosine is computed via

$\displaystyle \cos z \equiv \cos \Re z \cosh \Im z - \sin \Re z
\sinh \Im z.
$

Example

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))

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Samit K. Basu 2005-03-16