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ERF(3) Linux Programmer's Manual ERF(3)

erf, erff, erfl - error function

#include <math.h>
double erf(double x);
float erff(float x);
long double erfl(long double x);


Link with -lm.




Feature Test Macro Requirements for glibc (see
  feature_test_macros(7)):


erf():


_ISOC99_SOURCE ||
  _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE


 || /* Since glibc 2.19: */ _DEFAULT_SOURCE


 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE



erff(), erfl():

_ISOC99_SOURCE ||
  _POSIX_C_SOURCE >= 200112L


 || /* Since glibc 2.19: */ _DEFAULT_SOURCE


 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE








These functions return the error function of x, defined
  as



  

  










On success, these functions return the value of the error function
    of x, a value in the range [-1, 1].


If x is a NaN, a NaN is returned.


If x is +0 (-0), +0 (-0) is returned.


If x is positive infinity (negative infinity), +1 (-1) is
    returned.


If x is subnormal, a range error occurs, and the return
    value is 2*x/sqrt(pi).








See math_error(7) for information on how to determine
    whether an error has occurred when calling these functions.


The following errors can occur:



  

  
An underflow floating-point exception (FE_UNDERFLOW) is
    raised.




These functions do not set errno.








For an explanation of the terms used in this section, see
    attributes(7).



  

    Interface
    Attribute
    Value
  

  

    erf (), erff (), erfl ()
    Thread safety
    MT-Safe
  










C99, POSIX.1-2001, POSIX.1-2008.


The variant returning double also conforms to SVr4,
  4.3BSD.








cerf(3), erfc(3), exp(3)








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    2017-09-15
    GNU