Hi Boguslaw,
I underastand that you are calling a C++ ".dll" file in MATLAB which returns an array of type "clib.array.libname.Double". Further, due to the large size of the array, you're looking for a quick and effective method to convert this array into a MATLAB array for additional processing.
Assuming that the data is stored in a ".dat" file, You can leverage MATLAB "memmapfile" function to create a memory map to this file . This memory map can then access this file in the same way it accesses dynamic memory, accelerating file reading and writing, enabling you to work with data in the file as if it were a MATLAB array.
You can refer to the following documentation for more details about the MATLAB "memmapfile" function-
Hope this helps you to convert the described array into a MATLAB array for further processing.
Regards,
Vinayak Luha