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c99 [ flag... ] file... -lm [ library... ] #include <math.h> double sqrt(double x);

float sqrtf(float x);

long double sqrtl(long double x);

These functions compute the square root of their argument x.

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.

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.

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.

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE |

Interface Stability Standard |

MT-Level MT-Safe |

feclearexcept(3M), fetestexcept(3M), isnan(3M), math.h(3HEAD), attributes(5), standards(5)