# Expm1

Computes an exponential of vector elements decreased by 1.

## Syntax

Fortran:

call vsexpm1( n, a, y )

call vdexpm1( n, a, y )

C:

vsExpm1( n, a, y );

vdExpm1( n, a, y );

## Input Parameters

Name | Type | Description
--- | --- | ---
n | FORTRAN: INTEGER, INTENT(IN) C: int | Specifies the number of elements to be calculated.
a | FORTRAN: REAL, INTENT(IN) for vsexpm1 DOUBLE PRECISION, INTENT(IN) for vdexpm1 C: const float* for vsExpm1 const double* for vdExpm1 | FORTRAN: Array, specifies the input vector a. C: Pointer to an array that contains the input vector a.

Precision Overflow Thresholds for Expm1 Function
Data Type | Threshold Limitations on Input Parameters
--- | ---
single precision | `a[i] < Ln( FLT_MAX )`
double precision | `a[i] < Ln( DBL_MAX )`

## Output Parameters

Name | Type | Description
--- | --- | ---
y | FORTRAN: REAL for vsexpm1 DOUBLE PRECISION for vdexpm1 C: float* for vsExpm1 double* for vdExpm1 | FORTRAN: Array, specifies the output vector y. C: Pointer to an array that contains the output vector y.

Parent topic: Exponential and Logarithmic Functions