expm1-expm1f-expm1l.md

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expm1, expm1f, expm1l	API reference for expm1, expm1f, and expm1; which compute the base-e exponential of a value, minus one.	9/1/2020	expm1l expm1 expm1f	msvcrt.dll msvcr80.dll msvcr90.dll msvcr100.dll msvcr100_clr0400.dll msvcr110.dll msvcr110_clr0400.dll msvcr120.dll msvcr120_clr0400.dll ucrtbase.dll api-ms-win-crt-math-l1-1-0.dll	DLLExport	apiref	expm1l expm1 expm1f	expm1f function expm1l function expm1 function	2a4dd2d9-370c-42b0-9067-0625efa272e0

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
);
#define expm1(X) // Requires C11 or higher

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, unless you're using the <tgmath.h> macro to call this function, expm1 always takes and returns a double.

If you use the <tgmath.h> expm1() macro, the type of the argument determines which version of the function is selected. See Type-generic math for details.

Requirements

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

For more compatibility information, see Compatibility.

See also

Math and floating-point support
exp2, exp2f, exp2l
pow, powf, powl