expm1, expm1f, expm1l


For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.

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

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  


The floating-point exponential value.

The expm1 functions return a floating-point value that represents ex – 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.

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.

RoutineRequired header
expm1, expm1f, expm1l<math.h>

For additional compatibility information, see Compatibility.

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

Floating-Point Support
exp2, exp2f, exp2l
pow, powf, powl