Calculates the square root of a floating-point number

#include <math.h>
double sqrt ( double x  );
float sqrtf ( float x  );         (C99)
long double sqrtl ( long double x  );         (C99)

The sqrt( ) functions return the square root of the argument x. If the argument is less than zero, a domain error occurs.

Example

double x[ ] = { 0.5, 0.0, -0.0, -0.5 };

for ( int i = 0; i < ( sizeof(x) / sizeof(double) ); i++)
{
  printf("The square root of %.2F equals %.4F\n", x[i], sqrt( x[i] ) );
  if ( errno )
    perror( _  _FILE_  _ );
}

This code produces the following output:

The square root of 0.50 equals 0.7071
The square root of 0.00 equals 0.0000
The square root of -0.00 equals -0.0000
The square root of -0.50 equals NAN
sqrt.c: Numerical argument out of domain

sqrt( ) is also used in the examples shown at erf( ), feholdexcept( ), frexp( ) and signbit( ) in this chapter.

See Also

The complex arithmetic function csqrt( ); the cube root function cbrt( ) and the hypotenuse function, hypot( )