Copyright © 1997 The Open Group

asin - arc sine function

`#include <math.h> double asin(double`

x);

Theasin()function computes the principal value of the arc sine ofx.The value ofxshould be in the range [-1,1].An application wishing to check for error situations should set

errnoto 0, then callasin(). Iferrnois non-zero on return, or the return value is NaN, an error has occurred.

Upon successful completion,asin()returns the arc sine ofx, in the range [-_{}/2,_{}/2] radians. If the value ofxis not in the range [-1,1], and is not ±Inf or NaN, either 0.0 or NaN is returned anderrnois set to [EDOM].If

xis NaN, NaN is returned anderrnomay be set to [EDOM].If

xis ±Inf, either 0.0 is returned anderrnois set to [EDOM] or NaN is returned anderrnomay be set to [EDOM].If the result underflows, 0.0 is returned and

errnomay be set to [ERANGE].

Theasin()function will fail if:

- [EDOM]
- The value
xis not ±Inf or NaN and is not in the range [-1,1].The

asin()function may fail if:

- [EDOM]
- The value of
xis ±Inf or NaN.- [ERANGE]
- The result underflows.
No other errors will occur.

None.

None.

None.

isnan(),sin(),<math.h>.

Derived from Issue 1 of the SVID.

Copyright © 1997 The Open Group

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