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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.
Core Minimal Interpreter Commands
lasterr
Get or set the last error message.

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Discover Compose, including its language support and system requirements.
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The Compose tutorials and associated example model files help introduce you to the basic functionality of the software.
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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
    - &
      Logical conjunction, the 'and' operator.
    - &&
      Short circuit boolean and operator.
    - -
      Subtraction operator.
    - +
      Addition operator.
    - ==
      Equality comparison operator.
    - addlibrary
      Adds an existing library or a custom library to load the functions contained in it.
    - addpath
      Updates the search path for functions by adding the given directories d, ... to the existing path R.
    - addtoolbox
      Adds an existing toolbox or a custom toolbox to load the functions contained in it.
    - all
      Returns a logical that indicates whether all of the corresponding elements of the input are nonzero.
    - and
      Performs logical conjunction, the 'and' operation, equivalent to the & operator.
    - ans
      Returns the most recently computed result that was not assigned to a variable.
    - any
      Returns a logical that indicates whether any of the corresponding elements of the input are nonzero.
    - arg
      Returns the argument (angle) of each element of z in radians. The arguement is defined as atan2(imag(z),real(z)).
    - assert
      Sets an error if the given condition, s, is not satisfied. An optional input argument, errormessage may be used to customize the error displayed when assert fails.
    - assignin
      Assigns the value val to variable name var in context con.
    - break
      Ends execution of the nearest enclosing loop, even if the end condition for the loop has not been satisfied. break will not end execution of multiple, nested loops.
    - builtin
      Calls the built-in function f with given inputs, if applicable. If there is a custom function that overrides f, the custom function implementation will be ignored and the built-in function will be executed.
    - case
      case is used in switch statements and specifies a constant expression, expression, that the variable used in switch is compared with. The expression in each case label must be a constant and unique in the scope of the switch statement.
    - catch
      catch is used in try-catch blocks and is executed when an exception or error occurs in the try block.
    - class
      Retrieves the class type of the given input, x.
    - classdef
      Begins a class definition.
    - clc
      Clears the OML Command Window and moves the cursor to the top left position of the Command Window.
    - clear
      Obliterates variable(s) from memory in the current session of the application.
    - clearprofiledata
      Erases collected profile data.
    - clearvars
      Delete all or specified variable(s) from memory in the current session of the application. When no variable names are specified, delete all variables. When -except is specified, exclude the specified variable names from deletion.
    - composedir
      Returns the Compose installation root directory path.
    - continue
      Skips statements after continue and executes the next iteration of the loop.
    - disp
      Prints the value of x to the application's Command window.
    - display
      Prints the name and value of variable x.
    - .*
      Element-wise matrix multiplication operator.
    - else
      else is used in if-else statements and is executed when the if condition is not satisfied.
    - elseif
      Other statement in an if-else expression if no previous 'if' condition are met.
    - end
      Returns the last index of the collection being indexed.
    - eq
      Equality comparison, equivalent to the == operator.
    - error
      Displays a custom error message and ends execution.
    - errormsgonly
      Displays the error string s without any error stack information and ends the execution.
    - eval
      Evaluates the given expression.
    - evalin
      Same as eval except variable or expression is evaluated in context. Context is either 'caller' or 'base'.
    - exist
      Returns an integer (R) based on whether a variable, function, directory, or file with the name s exists in the current session.
    - exit
      Terminates the current session of the application.
    - false
      Returns false value(s).
    - feval
      Evaluates the specified function with the given input(s).
    - flintmax
      Returns the largest integer that can be represented by the string x.
    - for
      For loop is useful for executing many iterations of a statement.
    - format
      Sets the format for displaying numbers.
    - funccount
      Returns the number of registered built-in functions in the application.
    - funclist
      Displays the names of the registered built-in functions in the application.
    - function
      Used to define user-defined functions.
    - ge
      Perform greater than or equal comparison, equivalent to the >= operator.
    - genvarname
      Generates unique names which can be used for variables, based on the given input(s), s.
    - getargc
      Gets the number of command line arguments, argc, that the application is launched with.
    - getargv
      Gets the command line argument at the given index, index.
    - getcmdinput
      Gets the command line argument at position n supplied as part of the -input option while launching the application.
    - getenv
      Gets the value of the environment variable x, defined for the current session of the application.
    - getnumofcmdinputs
      Gets the number of command line arguments as part of the -input option while launching the application.
    - getprofiledata
      Returns collected profile data.
    - global
      Declares a list of variables as global. When a variable is declared as global it may be accessed within a function without being passed as a parameter. Variables must be declared as global in both the scope they are defined and the scope they are used.
    - >
      Greater than comparison operator.
    - >=
      Greater than or equal to comparison operator.
    - gt
      Greater than comparison, equivalent to the > operator.
    - help
      Shows help for the command name or built-in function func.
    - horzcat
      Returns the horizontal concatenation of x1,x2,...,xN along the 2nd dimension.
    - if
      Logical decision-making if statement. Can be combined with 'and' 'or' operators to create complex logical tables.
    - inf
      Returns infinite value(s).
    - input
      Displays a message, prompt, and interrupts script execution until you provide input.
    - inputname
      Indicate the variable name of the n-th argument passed into a function.
    - isa
      Returns result R if the input, v, belongs to the class, class.
    - isbatch
      Returns true if the application is running in batch mode.
    - isfloat
      Returns true if input is a scalar, complex, or matrix.
    - isinf
      Tests if a value is infinite.
    - ismatrix
      Tests if a value is a matrix.
    - isnan
      Tests if a value is not a number.
    - isnumeric
      Tests if a value is numeric.
    - isscalar
      Tests if a value is a scalar.
    - isvarname
      Tests if a string is a valid variable name.
    - keyboard
      Enters the keyboard mode, which interrupts the current script and evaluation of the interactive user input(s). To exit 'keyboard' mode: stop the script execution in the user interface, press the Esc key, or type 'return' or 'dbcont'.
    - lasterr
      Get or set the last error message.
    - lastwarn
      Displays or sets the last warning message.
    - ldivide
      Perform element-wise matrix left division, equivalent to the .\ operator.
    - le
      Less than or equal to comparison, equivalent to the <= operator..
    - \
      Left division of scalars and/or matrices operator.
    - .\
      Element-wise left matrix division operator.
    - <
      Less than comparison operator.
    - <=
      Less than or equal to comparison operator.
    - linspace
      Create a row vector with equally spaced elements.
    - logspace
      Create a row vector with logarithmically spaced elements.
    - lt
      Less than comparison, equivalent to the < operator
    - memoryuse
      Returns general data about memory used by the application process.
    - meshgrid
      Construct a grid of points from coordinate vectors.
    - methods
      Begins a methods block within a class definition.
    - minus
      Perform subtraction.
    - mislocked
      Returns true if the named function f is locked.
    - mldivide
      Perform left division of scalars and/or matrices, equivalent to the \ operator.
    - mlock
      Locks the function into memory meaning it cannot be cleared.
    - mpower
      Perform a matrix power operation, equivalent to the ^ operator.
    - ^
      Matrix power operator.
    - mrdivide
      Perform right division of scalars and/or matrices, equivalent to the / operator.
    - mtimes
      Perform matrix multiplication on a list of arguments from left to right, equivalent to the * operator.
    - *
      Multiplication operator.
    - munlock
      Unlocks the named function f. If no input is given then munlock unlocks the current function.
    - nan
      Abbreviation for Not A Number. If used as a built-in function returns an n x n or m x n matrix where each cell equals NaN.
    - nargin
      Returns the number of arguments required by a function, or the number of arguments received by a function, as detailed below.
    - narginchk
      Check for correct number of inputs.
    - nargout
      Returns the number of outputs.
    - nargoutchk
      Check for correct number of outputs.
    - ndgrid
      Construct a grid of points from coordinate vectors.
    - ne
      Perform inequality comparison, equivalent to the != operator.
    - normalize
      Normalize vectors.
    - not
      Performs logical negation, the 'not' operation.
    - ~
      Logical negation, the 'not' operator.
    - ~=
      Operator for inequality comparison.
    - omlpaginate
      Sets the pagination mode for the display of matrices, cell arrays, structs, and strings in sequence so it is easily readable.
    - or
      Performs logical disjunction, the 'or' operation, equivalent to the | operator.
    - |
      Logical disjunction, the 'or' operator.
    - savepath
      Save in a file an addpath function call for each path defined when the savepath command is executed. These paths can be restored in a future session by executing the saved file.
    - parcluster
      Indicate the number of threads desired in parallel loops
    - path
      Sets or displays the current search path for the application.
    - pause
      Interrupts execution of a script or code.
    - persistent
      Declares a list of variables as persistent. When a variable is declared as persistent, its value is retained after the function exits.
    - plus
      Perform addition on a list of arguments from left to right.
    - polyder
      Returns the coefficients of the derivative of the polynomial whose coefficients are given by the vector x.
    - power
      Perform power operation, applied to matrices on an element-wise basis, equivalent to the .^ operator.
    - .^
      Element-wise matrix power operator.
    - profile
      Enable/disable internal code profiling.
    - properties
      Begins a properties block within a class definition.
    - putenv
      Assigns the value of the environment variable x to value for the current session of the application.
    - quit
      Terminates the current session of the application.
    - :
      Range operator.
    - rdivide
      Perform element-wise matrix right division, equivalent to the ./ operator.
    - registerpath
      Extension of addpath to register a path used by a certain library created with the Library Manager. Call to the function It registers the library's function list.
    - rehash
      Clears any function definitions in memory so that the definitions are reread from the corresponding file.
    - removelibrary
      Removes a previously loaded OML library or a custom library.
    - restoredefaultpath
      Resets the current search path for functions to what it was at application startup.
    - return
      Returns control to OML interpreter.
    - ./
      Element-wise right matrix division operator.
    - /
      Right division of scalars and/or matrices operator.
    - rmpath
      Updates the search path for functions by removing the given directories d, ... from the existing path R.
    - run
      Executes the script s in the current session of the application. The script s either needs to contain the fully qualified path or must reside in the search paths for the current session of the application.
    - setenv
      Assigns the value of the environment variable x to value for the current session of the application.
    - ||
      Short circuit boolean 'or' operator.
    - skipformat
      Skips formatting output when displaying matrices of size greater than or equal to size, resulting in faster printing for large data sets as all elements are printed as floats.
    - sort
      Sorts elements of x into ascending order by default.
    - subsref
      Extract a subset of a collection given an indexing method and range. sub on the value val.
    - switch
      Just like an if-else statement but can only compare one variable. Each possibility is represented with a 'case' with the default case being 'otherwise'.
    - times
      Perform multiplication on a list of arguments from left to right, applied to matrices on an element-wise basis. Equivalent to the .* operator.
    - true
      Returns true value(s).
    - try
      try is used in try-catch blocks and is the code that is executed first in the sequence of the try-catch block. If there is an error in the try block, control is passed to the catch block, where exceptions are handled.
    - type
      Displays the type of input given.
    - uminus
      Unary minus sign.
    - uplus
      Unary plus sign.
    - varargin
      Specify that a function can take a variable number of arguments.
    - varargout
      Specifies that a function can return a variable number of outputs.
    - varlist
      Shows a list of variable names recognized by the interpreter.
    - verbose
      Sets the verbose level in the current session. If level is greater than 0, additional information is provided when the commands are executed. If no argument is provided, verbose returns the current setting.
    - version
      Gets the version of the application.
    - vertcat
      Vertically concatenates a1 through aN along the first dimension.
    - warning
      Prints the given input string, s, as a warning.
    - warningmsgonly
      Displays the string s as a warning, but without any warning stack information.
    - which
      Gives a brief description on the origin of a function.
    - while
      While loop that executes until the condition returns false.
    - who
      Returns the names of variables defined in the current session of the application.
    - whos
      Displays the names, sizes, memory used in bytes and the class or type of each variable defined in the current session of the application.
  - Data Structure Commands
  - Differential Equations Commands
  - Elementary Math Commands
  - 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!

lasterr

Get or set the last error message.

Syntax

msg = lasterr()

lasterr(new_message)

Inputs

new message: Message to set as the last message error.; Type: char | string; Dimension: string

Outputs

msg: A string: message of the last error.

Examples

error('this is my error message.');
msg = lasterr()

In this example, the function eps('toto') raises an error; the error message should display:

message_computed = '';
try
  eps('toto')
catch
  message_computed = lasterr();
end
expected_message = 'Error: invalid class name';
if strcmp(message_computed, expected_message) ~= 1
  error('it is not the error expected.');
end

Comments

lasterr() is generally used with try catch statement to compare the error message and do an action in response of this error. lasterr('') can be used to reset the last error message. Clear does not modify the last error message.