add is_matlab_online()

Author: scivision

+stdlib/is_matlab_online.m

@@ -0,0 +1,19 @@
+%% IS_MATLAB_ONLINE check if running in MATLAB Online
+% This function is heuristic check using undocumented environment variables.
+% These variables have worked across several Matlab releases, but there isn't a guarantee
+% that they will always be present or have the same values.
+
+function y = is_matlab_online()
+
+y = isunix() && ~ismac();
+if ~y, return, end
+
+h = getenv("MW_DDUX_APP_NAME");
+
+if h == "MATLAB_ONLINE"
+  y = true;
+else
+  y = false;
+end
+
+end