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       expm1, expm1f, expm1l - exponential minus 1


       #include <math.h>

       double expm1(double x);
       float expm1f(float x);
       long double expm1l(long double x);

       Link with -lm.

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

       expm1(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
       _ISOC99_SOURCE; or cc -std=c99
       expm1f(), expm1l(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
       || _ISOC99_SOURCE; or cc -std=c99


       expm1(x) returns a value equivalent to

           exp(x) - 1

       It is computed in a way that is accurate even if the value of x is near
       zero—a case where exp(x) - 1 would be inaccurate due to subtraction  of
       two numbers that are nearly equal.


       On success, these functions return exp(x) - 1.

       If x is a NaN, a NaN is returned.

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

       If x is positive infinity, positive infinity is returned.

       If x is negative infinity, -1 is returned.

       If the result overflows, a range error occurs, and the functions return
       -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively.


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

       The following errors can occur:

       Range error, overflow
              An overflow floating-point exception (FE_OVERFLOW) is raised.

       These functions do not set errno.


       C99, POSIX.1-2001.


       For  some large negative x values (where the function result approaches
       -1), expm1() raises a bogus underflow floating-point exception.

       For some large positive  x  values,  expm1()  raises  a  bogus  invalid
       floating-point   exception   in   addition  to  the  expected  overflow
       exception, and returns a NaN instead of positive infinity.


       exp(3), log(3), log1p(3)


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       be found at

                                  2008-08-05                          EXPM1(3)