1atan(3M)                Mathematical Library Functions                atan(3M)
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NAME

6       atan, atanf, atanl - arc tangent function
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SYNOPSIS

9       c99 [ flag... ] file... -lm [ library... ]
10       #include <math.h>
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12       double atan(double x);
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15       float atanf(float x);
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18       long double atanl(long double x);
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DESCRIPTION

22       These functions compute the principal value of the arc tangent of x.
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RETURN VALUES

25       Upon successful completion, these functions return the arc tangent of x
26       in the range [−pi/2,pi/2] radians.
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29       If x is NaN, NaN is returned.
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32       If x is ±0, x is returned.
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35       If x is ±Inf, ±pi/2 is returned.
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ERRORS

38       No errors are defined.
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ATTRIBUTES

41       See attributes(5) for descriptions of the following attributes:
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46       ┌─────────────────────────────┬─────────────────────────────┐
47       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
48       ├─────────────────────────────┼─────────────────────────────┤
49       │Interface Stability          │Standard                     │
50       ├─────────────────────────────┼─────────────────────────────┤
51       │MT-Level                     │MT-Safe                      │
52       └─────────────────────────────┴─────────────────────────────┘
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SEE ALSO

55       atan2(3M),  isnan(3M),  math.h(3HEAD),  tan(3M),  attributes(5),  stan‐
56       dards(5)
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60SunOS 5.11                        12 Jul 2006                         atan(3M)
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