HP-UX Reference (11i v1 05/09) - 3 Library Functions A-M (vol 6)

atand(3M) atand(3M)

NAME

atand(), atandf( ) - degree-valued arctangent functions

SYNOPSIS

#include <math.h>

double atand(double x);

float atandf(float x);

DESCRIPTION

atand() is a degree-valued version of the

atan() function. It returns the arctangent of x in the range

−90 to 90.

atandf() is a float version of atand()

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

atand() and atandf() are not speciﬁed by any standard, but

atandf() is named in accordance with

the conventions speciﬁed in the "Future Library Directions" section of the ANSI C standard.

To use these functions, compile either with the default

-Ae option or with the -Aa and

-D_HPUX_SOURCE options. Make sure your program includes <

math.h>. Link in the math library by

specifying

-lm on the compiler or linker command line.

RETURN VALUE

If x is ±INFINITY, atand() returns ±90 respectively.

If x is NaN,

atand() returns NaN.

If the correct value after rounding would be smaller in magnitude than MINDOUBLE, atand() returns

zero.

ERRORS

No errors are deﬁned.