Modify the value of a Matrix in the Base Workspace from a Simulink Block's Callback (or Initialization)

Hi, I would like to build a Subsystem that, before the Model Simulation, modifies the values of a variable (a Matrix) in the Base Workspace (I need that it appens before the Model Simulation because other blocks in the Model use the variable during the simulation). I thought that a good solution could be to use the Subsystem Callback or the Mask Initialization, but I had some problems in writing the Matrix Values in the Base Worspace.

[lokender Rawat]

What problems are you facing when writing the values to the Base Workspace ? Could you elaborate more on this ?