Precedence

The MATLAB interpreter of SIMO considers a sequence of characters as a variable name or a function name, when the sequence satisfies the following requirements:

• The sequence does not start with a number or an underscore.
• Each character of the sequence is a letter (uppercase or lowercase), a number, or an underscore.

When such a sequence of characters is found, the interpreter attempts to look for a variable or a function with the name equal to the sequence of characters. It is possible that a variable and a function have identical names. In this case, instead of throwing an error immediately, the interpreter decides which one, the function or the variable, to execute. The following two flow charts show how such a decision is made.

For the first flow chart below, a name is entered with neither parentheses nor input arguments.

The above flow chart is explained in the following.

1. Attempt to run an expression, say, fun. No input argument is given. fun can be

   • one of the expressions being run in the console,
   • one of the expressions in the script being run from the editor,
   • one of the expressions in the body of a main or local function, or
   • the expression of an anonymous function.

2. Check if fun is a built-in function. If it is, it attempts to run the function.

3. Check if fun matches any of the variables in the current workspace.

   • If fun is run from the console or editor, it searches the global workspace.
   • If fun is run from the body of a main or local function, it searches the workspace of the function body.
   • If fun is run in an anonymous function, it searches the workspace of the anonymous function.

4. If the variable fun is found in Step 3 above, return the variable.

5. If the variable fun is not found in Step 3 above, search for the file fun.m in the work folder.

6. If fun.m exists in the work folder mentioned in Step 5 above, check if a main function is defined in fun.m. If yes, run fun as a main function. Otherwise, run run as a script.

7. If the expression run in Step 1 was i or j, it returns a unit imaginary number. Otherwise, an error is throw.

For the flow chart below, a name is entered with

• a pair of parentheses and input arguments,
• or a pair of parentheses but no input arguments.

1. Attempt to run fun(a1,a2,...) or fun(). Here, a1, a2, ... are input arguments. The expression can be

   • one of the expressions run in the console,
   • one of the expressions in the script run from the editor,
   • one of the expressions in the body of a main or local function, or
   • the expression of an anonymous function.

2. Check if fun is a built-in function. If it is, it attempts to run the function.

3. Check if fun matches any of the variables in the current workspace.

   • If it is run from the console or editor, it searches the global workspace.
   • If it is run in the body of a main or local function, it searches the workspace of the function body.
   • If it is run in the body of an anonymous function, it searches the workspace of the anonymous function.

4. The variable fun found in Step 3 above could be a function handle or local function. In both cases, run the corresponding function. But, if it is an array, return its value.

5. If the variable fun is not found in Step 3 above, search for the file fun.m in the work folder.

6. If fun.m exists in the work folder mentioned in Step 5 above, check if a main function is defined in fun.m. If yes, run fun as a function. Otherwise, throw an error since a script should not be run with input arguments or parentheses.