Matlab/Simulink S-Function: How to print to the command line

In Matlab/Simulink, you can print to the command line where Matlab was started using fprintf(stderr, ...). This is useful for debugging purposes.

At least in my setup, stdout is redirected, so printf does not work as expected. However, fprintf(stderr, ...) works fine.

fprintf(stderr, "Hello S-Function\n");

This can be used anywhere in the S-function.