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#include <math.h> double atan(double x); |
This function computes the angle, in the range [-Pi/2..Pi/2]
radians, whose tangent is x.
The arc tangent, in radians, of x. If x is a NaN
,
the return value is NaN
and errno
is set to EDOM
.
If x is a positive or negative Inf
, the return value is
equal to positive or negative Pi/2
, respectively, and
errno
is left unchanged.
ANSI/ISO C | C89; C99 |
POSIX | 1003.2-1992; 1003.1-2001 |