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sqrt

Square root function

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Contents

Interface
Description
Special Values
Standards
Compatibility
Page Comments

Interface

#include <math.h>

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

#include <complex.h>

	complex	`sqrt` (complex x)
	double complex	`csqrt` (double complex x)
	float complex	`csqrtf` (float complex x)
	long double complex	`csqrtl` (long double complex x)

Description

The sqrt function computes the non-negative square root of x, i.e

sqrt(x) $=\sqrt x$

For complex numbers x, sqrt returns the complex root of x, using the following formula

(1)

$\sqrt{x} = \sqrt { \mathrm{abs}(x)} \left[ \cos\left(\frac{\mathrm{arg}(x)}{2}\right) +_ i \sin\left(\frac{\mathrm{arg}(x)}{2}\right) \right]$

where $\mathrm{arg}(x)$ is the argument of x.

Example 1:

#include <stdio.h>
#include <math.h>
 
int main()
{
  double x = 1234321;
  double result = sqrt(x);
  printf("The square root of %.2lf is %.2lf\n", x, result);
  return 0;
}

Ouput:

The square root of 1234321.00 is 1111.00

Special Values

sqrt ( -0 ) returns -0.
sqrt ( x ) returns a NaN and generates a domain error for x < 0.

Standards

The sqrt function conforms to ISO/IEC 9899:1999(E).

Compatibility

	DOS	UNIX	Windows	ANSI C	C++ only
sqrtl	•		•
Real sqrt	•	•	•	•
Complex sqrt	•		•		•
Complex csqrt		•			•

Last Modified: 2009-11-01 08:42:53 Page Rendered: 2010-02-09 12:39:48

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