Why does mxCreateDoubleMatrix() returns NULL?

I am using the following MATLAB External Interface API, to create a double matrix

>> mxCreateDoubleMatrix(3,3,mxREAL)

It returns NULL, why?

Answer 1

[MathWorks Support Team]

Call the following API before using 'mxCreateDoubleMatrix'

>> mclInitializeApplication 

This sets up the application state shared by all MATLAB Runtime instances created in the current process. For more information on this API, you can view the release-specific documentation by executing the following command in the MATLAB R2020a command window:

>> web(fullfile(docroot, 'compiler_sdk/cxx/mclinitializeapplication.html'))

For further information regarding the current release, please follow the link below:

https://www.mathworks.com/help/