Home
Reference Guides
Reference guides are available for functions and commands supported by OML, Tcl, and Python.
Reference Guide for OpenMatrix Language Functions
The Reference Guide contains documentation for all functions supported in the OpenMatrix language.
Elementary Math Commands
expm1
Exponential of the argument, minus one.

Welcome
What's New
Discover new features and enhancements.
Get Started
Discover Compose, including its language support and system requirements.
Tutorials
The Compose tutorials and associated example model files help introduce you to the basic functionality of the software.
User Guide
Learn about the features and functionality available in Compose.
Reference Guides
Reference guides are available for functions and commands supported by OML, Tcl, and Python.
- Scripting Guide for OpenMatrix Language
  OpenMatrix is a mathematical scripting language.
- Reference Guide for OpenMatrix Language Functions
  The Reference Guide contains documentation for all functions supported in the OpenMatrix language.
  - ABF Commands
  - Altair Integration Commands
  - Audio Commands
  - CAE Commands
  - CAE Reader Commands
  - CAE Reader 3D Commands
  - CAE Writer Commands
  - Calculus Commands
  - Computer Vision Commands
  - Communication Commands
  - Control System Commands
  - Core Minimal Interpreter Commands
  - Data Structure Commands
  - Differential Equations Commands
  - Elementary Math Commands
    - abs
      Returns the absolute value of a scalar/matrix/complex number.
    - accumarray
      Array accumulation.
    - angle
      Returns the phase angle of z equal to atan2(imag(z), real(z)).
    - bi2de
      Converts numbers from binary or a specified base to their decimal equivalents.
    - bin2dec
      Converts binary numbers to their decimal equivalents.
    - cart2pol
      Converts Cartesian coordinates to polar or cylindrical.
    - cart2sph
      Converts Cartesian coordinates to spherical.
    - ceil
      Returns the smallest integer that is greater than or equal to x.
    - circshift
      Circular shift.
    - complex
      Returns a complex number composed of real elements.
    - conj
      Return the complex conjugate.
    - cplxpair
      Sorts x into its ascending pairs by real part.
    - cumprod
      The cumulative product of object's elements along a specified dimension.
    - cumsum
      The cumulative sum of an object's elements along a specified dimension.
    - de2bi
      Converts non-negative integers to their equivalents in binary or a specified base.
    - dec2bin
      Converts non-negative integers to their binary equivalents.
    - dec2hex
      Converts non-negative integers to their hexadecimal equivalents.
    - diag
      Creates a diagonal matrix or returns the diagonal elements of a matrix on diagonal k.
    - diff
      Returns a vector or matrix of differences.
    - double
      Converts A into double precision type.
    - e
      Symbol for the base of the natural logarithm.
    - eps
      The spacing between two adjacent numbers in a given machine's floating point system, Epsilon.
    - exp
      For each element of x, returns e^x.
    - expm1
      Exponential of the argument, minus one.
    - eye
      Returns an identity matrix.
    - factor
      Returns the prime factorization of X. If two outputs are requested, returns the unique primes of X.
    - find
      Returns the position of non-zero elements in a matrix.
    - fix
      Rounds X down to zero.
    - flip
      Returns R, which is the matrix, m, flipped along the axis, a.
    - fliplr
      Returns R, which is the matrix, m, with its columns flipped left to right.
    - flipud
      Returns R, which is the matrix, m, with its rows flipped from top to bottom.
    - floor
      Returns the largest integer that is not greater than x.
    - gcd
      Returns the greatest common deviser of the set x.
    - hex2dec
      Converts hexadecimal numbers to their decimal equivalents.
    - i
      The imaginary number i, such that i^2 = -1
    - imag
      Returns the imaginary component of a complex number.
    - ind2sub
      Returns subscript from the linear index ind.
    - intersect
      Returns the elements that are common to two sets, without duplication.
    - ipermute
      Generalized reversing transpose of a matrix, using a permutation vector.
    - isbool
      Determines if x is a logical value.
    - iscomplex
      Determines if x is a complex value.
    - isempty
      Determines if x is an empty value.
    - isequal
      Compares x1,x2,... to each other; if all are equal, returns boolean value true, otherwise returns false.
    - isglobal
      Returns a logical value indicating whether the input is global in scope.
    - islogical
      Determines if x is a logical value.
    - ismember
      Determine which elements of the first argument exist in the second argument.
    - isprime
      Determines if x is a prime number.
    - isreal
      Determines if x is a real number.
    - issorted
      Returns true if the array x sorted by mode. By default mode is ascending.
    - isvector
      Determines if x is a vector.
    - j
      The imaginary number i, such that i^2 = -1.
    - lcm
      Least common multiple.
    - length
      Returns the length of an object's largest dimension.
    - log
      Computes the natural log for each element of x.
    - log1p
      Natural logarithm of one plus the argument.
    - log2
      Computes the base-2 logarithm of a matrix.
    - log10
      Computes the base-10 logarithm for each element of x.
    - logical
      Converts x to a logical type.
    - max
      Returns maximum values.
    - min
      Returns minimum values.
    - mod
      Returns x modulo y.
    - ndims
      Returns the number of dimensions of an array.
    - nextpow2
      Computes the exponent of the smallest power of 2 that is greater than or equal to the input in magnitude.
    - numel
      Returns the number of elements in x.
    - ones
      Returns a matrix of ones.
    - permute
      Generalized transpose of a matrix, using a permutation vector.
    - pi
      Symbol for pi.
    - pol2cart
      Converts polar or cylindrical coordinates to Cartesian.
    - pow2
      Computes powers of 2.
    - primes
      Returns all primes up to X.
    - prod
      Returns vector or matrix element products.
    - rank
      Computes the rank of matrix A.
    - rat
      Returns a rational approximation of the input using a continued fraction approximation.
    - real
      Returns the real part of x.
    - realmax
      Returns a matrix whose elements are all the largest floating point number that is representable.
    - realmin
      Returns a matrix whose elements are all the smallest normalized floating point number that is representable.
    - rem
      The resulting remainder of x / y.
    - repmat
      Replicates an input to create a block matrix with the number of specified replications in each dimension.
    - reshape
      Returns a matrix with the same elements as the input, but with reassigned dimensions.
    - rot90
      Returns R, the result of rotating matrix, m, in 90-degree succession(s).
    - round
      Rounds values to specified precision.
    - setdiff
      Returns the subset of the first set that does not belong to the second set.
    - setxor
      Returns the elements contained in either of two sets, but not in their intersection.
    - shiftdim
      Shift dimensions.
    - sign
      Returns the sign of the value passed in.
    - single
      Marks the given input in as a single precision data type. Single precision data can be used in the save command to write with single precision in .mat files.
    - size
      Returns the size of each dimension of an object.
    - sph2cart
      Converts spherical coordinates to Cartesian.
    - sqrt
      Returns the square root of each element of x.
    - squeeze
      Removes singular dimensions from a matrix.
    - sub2ind
      Converts subscript to a linear index.
    - sum
      Returns vector or matrix element sums.
    - union
      Returns the elements contained in either of two sets, without duplication.
    - unique
      Returns the elements of a set, without duplication.
    - vec2mat
      Converts a vector, v, to a matrix with the specified number of columns, c.
    - zeros
      Creates a matrix of zeros.
  - File I/O Commands
  - Geometry Commands
  - GUI Commands
  - HDF5 Reader Commands
  - HDF5 Writer Commands
  - hstpyfit Commands
  - Image Commands
  - JSON Commands
  - Library Manager Commands
  - Linear Algebra Commands
  - Logical Commands
  - Machine Learning Commands
  - Optimization Commands
  - Plotting Commands
  - PSIM Commands
  - Polynomial Math Commands
  - Signal Processing Commands
  - Special Functions Commands
  - Statistical Analysis Commands
  - String Operations Commands
  - System Commands
  - Table Commands
  - Tcl Bridge OML Commands
  - Tcl Bridge Tcl Commands
  - Time Commands
  - Trigonometry Commands
  - OML to Python Bridge Commands
  - Python to OML Bridge Commands
- Python in Compose Reference Guide
Appendix
Get help for the optional libraries that are available in the Extension Manager.
Frequently Asked Questions
You've got questions? We've got answers!

expm1

Exponential of the argument, minus one.

Syntax

R = expm1(x)

Inputs

x: Type: double | complex; Dimension: scalar | vector | matrix

Outputs

R: The returned values.; Dimension: scalar | vector | matrix.

Example

Show that expm1(x) has better accuracy than exp(x) - 1 for small real values of x

x = 1e-18;
a = exp(x)-1

a = 0

b = expm1(x)

b = 1e-18

The value of a has lost precision, but b has not.