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man pages section 3: Extended Library Functions, Volume 2

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Updated: Thursday, June 13, 2019
 
 

sqrtl(3M)

Name

sqrt, sqrtf, sqrtl - square root function

Synopsis

c99 [ flag... ] file... –lm [ library... ]
#include <math.h>

double sqrt(double x);
float sqrtf(float x);
long double sqrtl(long double x);

Description

These functions compute the square root of their argument x.

Return Values

Upon successful completion, these functions return the square root of x.

For finite values of x < −0, a domain error occurs and either a NaN (if supported) or an implementation-defined value is returned.

If x is NaN, a NaN is returned.

If x is ±0 or +Inf, x is returned.

If x is −Inf, a domain error occurs and a NaN is returned.

Errors

These functions will fail if:

Domain Error

The finite value of x is < −0 or x is −Inf.

If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the invalid floating-point exception is raised.

The sqrt() function sets errno to EDOM if the value of x is negative.

Usage

An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.

An application can also set errno to 0 before calling sqrt(). On return, if errno is non-zero, an error has occurred. The sqrtf() and sqrtl() functions do not set errno.

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
Availability
system/library/math
MT-Level
MT-Safe
Standard

See Also

math.h(3HEAD), feclearexcept(3M), fetestexcept(3M), isnan(3M), attributes(7), standards(7)