csqrt(), csqrtf(), csqrtl()

Updated: October 26, 2022

Compute the square root of a complex number


#include <complex.h>

double complex csqrt( double complex z );

float complex csqrtf( float complex z );

long double complex csqrtl( long double complex z );


The complex value that you want to get the square root of.


The general-purpose math library.
(QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.


These functions compute the square root of the complex number specified by z, with a branch cut along the negative real axis.

To check for error situations, use feclearexcept() and fetestexcept(). For example:


The square root of z.

If z is: These functions return: Errors:
±0 + 0i 0 + 0i
x + Infi Inf + Infi, even if x is NaN
x + NaNi NaN + NaNi, for finite x
-Inf + yi 0 + Infi, for finite positive y
Inf + yi Inf + 0i, for finite positive y
-Inf + NaNi NaN ± Inf, where the sign of imaginary part is unspecified
Inf + NaNi Inf + NaNi
NaN + yi NaN + NaNi FE_INVALID
NaN + NaNi NaN + NaNi

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.


C11, POSIX 1003.1

Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes