HP-UX Reference (11i v1 05/09) - 3 Library Functions N-Z (vol 7)

tan(3M) tan(3M)

NAME

tan(), tanf() - tangent functions

SYNOPSIS

#include <math.h>

double tan(double x);

float tanf(float x);

DESCRIPTION

tan() returns the tangent of x (x speciﬁed in radians).

tan() may lose accuracy when x is far from zero.

tanf() is a float version of tan()

; it takes a float argument and returns a float result. To use

this function, compile either with the default

-Ae option or with the -Aa and -D_HPUX_SOURCE

options.

tanf() is not speciﬁed by any standard, but it is named in accordance with the conventions speciﬁed in

the "Future Library Directions" section of the ANSI C standard.

To use these functions, make sure your program includes <math.h>, and link in the math library by speci-

fying -lm on the compiler or linker command line.

Millicode versions of the tan() and tanf() functions are available. Millicode versions of math library

functions are usually faster than their counterparts in the standard library. To use these versions, compile

your program with the +Olibcalls or the +Oaggressive optimization option.

If an error occurs, the millicode versions return the value described in the RETURN VALUE section, but do

not set

errno.

For more information, see the HP-UX Floating-Point Guide.

RETURN VALUE

If x is NaN or ±INFINITY,

tan()

returns NaN.

If the correct value after rounding would be smaller in magnitude than

MINDOUBLE, tan() returns zero.

If the correct value would overﬂow,

tan() returns ±HUGE_VAL and sets errno to [ERANGE].

ERRORS

tan() fails, errno is set to the following value.

[ERANGE] The correct value would overﬂow.