May 2, 1991 COS 3

### NAME

cos, cosf - cosine function

### LIBRARY

Math Library (libm, -lm)

### SYNOPSIS

```double` cos(```double x`)
```float` cosf(```float x`)

### DESCRIPTION

The cos(``) and cosf(``) functions compute the cosine of ```x` (measured in radians). A large magnitude argument may yield a result with little or no significance. For a discussion of error due to roundoff, see math(3).

### RETURN VALUES

The cos(``) function returns the cosine value.

### SEE ALSO

acos(3), asin(3), atan(3), atan2(3), cosh(3), math(3), sin(3), sinh(3), tan(3), tanh(3)

### STANDARDS

The cos(``) function conforms to ANSI X3.159-1989 (``ANSI C89'') .