expm1, expm1f, expm1l

Article
12/18/2017

The latest version of this topic can be found at expm1, expm1f, expm1l.

Computes the base-e exponential of a value, minus one.

Syntax

double expm1(   
   double x   
);  
float expm1(  
   float x  
);  // C++ only  
long double expm1(  
   long double x  
);  // C++ only  
float expm1f(  
   float x  
);  
long double expm1l(  
   long double x  
);

Parameters

x
The floating-point exponential value.

Return Value

The expm1 functions return a floating-point value that represents e^x – 1, if successful. On overflow, expm1 returns HUGE_VAL, expm1f returns HUGE_VALF, expm1l returns HUGE_VALL, and errno is set to ERANGE. For more information about return codes, see errno, _doserrno, _sys_errlist, and _sys_nerr.

Remarks

Because C++ allows overloading, you can call overloads of expm1 that take and return float and long double values. In a C program, expm1 always takes and returns a double.

Requirements

Routine	Required header
`expm1`, `expm1f`, `expm1l`	<math.h>

For additional compatibility information, see Compatibility.

.NET Framework Equivalent

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.