expm1

expm1

Compute the exponential function minus 1

Portability: C99

SYNOPSIS
DESCRIPTION
RETURN VALUE
DIAGNOSTICS
RELATED FUNCTIONS
SEE ALSO

SYNOPSIS

   #include <math.h>

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

DESCRIPTION

exmp1 computes the exponential function of its argument x. This function is expressed by the relation:

[IMAGE]

where e is the base of natural logarithms, 2.7128...

The function name expm1f should be used for float arguments, and expm1l for long double arguments. Alternately, if the header file tgmath.h is included, expm1 may be used with any numeric argument type.

RETURN VALUE

expm1 returns the exponential function of its argument minus 1, provided this value is expressible.

DIAGNOSTICS

If the result of expm1 is too large to represent, it returns HUGE_VAL in hexadecimal floating point, and either infinity or the largest finite value in binary floating point, depending on the rounding mode. In this case, the run-time library writes an error message to the standard error file (stderr).

If an error occurs in expm1, the _matherr or _matherb routine is called. You can supply your own version of _matherr or _matherb to suppress the diagnostic message or modify the value returned.

RELATED FUNCTIONS

exp, log1p, _matherb, _matherr

SEE ALSO

"Mathematical Functions" in Chapter 2, "Function Categories"

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