1atan(3M) Mathematical Library Functions atan(3M)
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6 atan, atanf, atanl - arc tangent function
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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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22 These functions compute the principal value of the arc tangent of x.
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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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38 No errors are defined.
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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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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)