expm1
Compute exp(X)-1
accurately for small
X
Syntax
Description
Examples
Calculate exp(X)-1
Accurately for Small X
Compare the accuracy of exp(X)-1
and expm1(X)
.
Create a vector of small real values.
X = [-1e-17 1e-15 2e-14]
X = 1×3
10-13 ×
-0.0001 0.0100 0.2000
Calculate exp(X)-1
using the exp
function.
Y = exp(X)-1
Y = 1×3
10-13 ×
0 0.0111 0.1998
The results can be zeros or have large relative errors. For example, Y(2)
is not close to X(2)
, which is 1e-15
.
Y(2)
ans = 1.1102e-15
Calculate exp(X)-1
using the expm1
function.
Y = expm1(X)
Y = 1×3
10-13 ×
-0.0001 0.0100 0.2000
In this case, where expm1(X)
is approximately X
, the results are more accurate. For example, Y(2)
is now close to X(2)
, which is 1e-15
.
Y(2)
ans = 1.0000e-15
Input Arguments
X
— Input array
scalar | vector | matrix | multidimensional array | table | timetable
Input array, specified as a scalar, vector, matrix, multidimensional array, table, or timetable.
Data Types: single
| double
| table
| timetable
Complex Number Support: Yes
Extended Capabilities
Tall Arrays
Calculate with arrays that have more rows than fit in memory.
The
expm1
function fully supports tall arrays. For more information,
see Tall Arrays.
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Thread-Based Environment
Run code in the background using MATLAB® backgroundPool
or accelerate code with Parallel Computing Toolbox™ ThreadPool
.
This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.
GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.
The expm1
function
fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray
(Parallel Computing Toolbox). For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).
Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.
This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).
Version History
Introduced before R2006aR2023a: Perform calculations directly on tables and timetables
The expm1
function can calculate on all variables within a table or
timetable without indexing to access those variables. All variables must have data types
that support the calculation. For more information, see Direct Calculations on Tables and Timetables.
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