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Matlab

  

defined

  

check the existence of a variable in an open MATLAB(R) session

 

Calling Sequence

Parameters

Description

Examples

Calling Sequence

defined(M, attribute)

Parameters

M

-

string naming the MATLAB® variable to be tested

attribute

-

(optional) where attribute is one of 'variable', 'function', or 'globalvar'

Description

• 

The command defined determines whether the variable M is defined in MATLAB®. By default, when no attribute parameter is specified, the defined command checks whether a variable named M exists in the MATLAB® environment.

• 

If the command contains the optional parameter 'function', then defined returns a value of 'true' only if a function named M is defined in the MATLAB® environment. The option 'globalvar' returns 'true' if the variable M is defined in the MATLAB® environment and it is a global variable.

• 

To set a global variable in MATLAB®, define the variable as a global by using Matlab[setvar], with the optional parameter 'globalvar' as in the calling sequence Matlab[setvar]("M", value, 'globalvar'). Variables must be declared as global to work with functions that use global variables of the same name.

• 

The defined command establishes whether M exists in the MATLAB® session.  Executing the defined command returns either 'true' or 'false'.

Examples

Setting a Maple matrix in MATLAB®.

withMatlab:

maplematrix_aLinearAlgebra[RandomMatrix]2

Matlab[setvar]matlabmatrix_a,maplematrix_a

The existence of the matrix in MATLAB® is now checked.

Matlab[defined]matlabmatrix_a

true

Note here that the matrix defined in Maple is not defined in MATLAB®

Matlab[defined]maplematrix_a

false

This example assumes that a MATLAB® function has been saved in the file example.m

% multiply the input value x by the global variable y

  function ret=example(x)

      global y

      ret=x*y;

Matlab[setvar]y,10.123,'globalvar'

Matlab[defined]y,'globalvar'

true

Matlab[defined]example,'function'

true

Matlab[defined]y,'variable'

true

Matlab[evalM]answer = example(2)

Matlab[getvar]answer

20.246

See Also

Matlab

Matlab[evalM]

Matlab[getvar]

Matlab[setvar]

MatlabMatrix

 


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