| MATLAB Function Reference | ![]() |
Y = cos(X)
The cos function operates element-wise on arrays. The function's domains and ranges include complex values. All angles are in radians.
Y = cos(X) returns the circular cosine for each element of X.
Graph the cosine function over the domain
.
x = -pi:0.01:pi; plot(x,cos(x)), grid on

The expression cos(pi/2) is not exactly zero
but a value the size of the floating-point accuracy, eps, because pi is only a floating-point approximation
to the exact value of
.
The cosine can be defined as

cos uses FDLIBM, which was developed at SunSoft, a Sun Microsystems™ business, by Kwok C. Ng, and others. For information about FDLIBM, see http://www.netlib.org.
cosd, cosh, acos, acosd, acosh
![]() | corrcoef | cosd | ![]() |
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