C Language and Libraries Help (clang.hlp) (Table of Contents; Topic list)
sqrt, _sqrtl
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─────Run-Time Library───────────────────────────────────────────────────────
 
  Include:   <math.h>, <errno.h>
 
  Syntax:    double sqrt( double x );
             long double _sqrtl( long double x );
 
  Returns:   a square root if successful, or 0 if not.
             errno: EDOM
 
  See also:  pow, exp, ldexp, _ldexpl, frexp, log, _matherr
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