tan(), tanf(), tanl()

Calculate the tangent of an angle

Synopsis:

#include <math.h>

double tan( double x );

float tanf( float x );

long double tanl( long double x );

Arguments:

x: The angle, in radians, for which you want to compute the tangent.

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

These functions compute the tangent of x radians. A large magnitude argument may yield a result with little or no significance.

To check for error situations, use feclearexcept() and fetestexcept(). For example:

Call feclearexcept(FE_ALL_EXCEPT) before calling tan(), tanf(), or tanl().
On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

Returns:

The tangent value.

If `x` is:	These functions return:	Errors:
±0.0	`x`	—
±Inf	NaN	FE_INVALID
NaN	NaN	—
Subnormal	`x`	—

Note: The tangent function has mathematical poles at ..., -π/2, π/2, 3 * π/2, ..., but these numbers can't be expressed exactly in floating-point representation, so no FE_DIVBYZERO errors occur.

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

Examples:

#include <stdio.h>
#include <math.h>
#include <fenv.h>
#include <stdlib.h>

int main( void )
{
    int except_flags;

    feclearexcept(FE_ALL_EXCEPT);

    printf( "%f\n", tan(.5) );

    except_flags = fetestexcept(FE_ALL_EXCEPT);
    if(except_flags) {
        /* An error occurred; handle it appropriately. */
    }

    return EXIT_SUCCESS;
}

produces the output:

0.546302

Classification:

ANSI, POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	No
Thread	Yes