User Function

This section explains user function.

In software, it is very useful to summarize some common programs as functions.

This section shows process of creating, saving, loading and calling a function. Specific process of creating a user function is shown in figure below:

User Function

Create

To create a function, use function...end; block.

For example, to create a function named “realsqrt”, see code as follows:

function Y = realsqrt(X)
    Y = sqrt(X);
    if(any(any(imag(Y))))
        error("realsqrt: realsqrt generate complex results");
    end
end;

Function names follow same rules as variable names. Name must start with a letter and can contain letters, numbers, or underscores.

For more details, see Function.

Save

The created user function realsqrt is saved as “usr_realsqrt.msf”.

Function name and file name should be consistent to facilitate practical application. Example intuitively shows difference between function name and file name.

Note:

• The naming rules of file follow function naming rules;
• File extension is .msf.

Load

Import user function using built-in function load, see Saving and Importing Data.

To load a user function, use full path of function file. After loaded, function is displayed in Script workspace.

load("D:/usr_realsqrt.msf");

Call

For a successfully imported user function, invoke this function by name in the script.

a = [1,4,9];
b = realsqrt(a)

After function realsqrt is invoked successfully, result is printed in Script console:

a = [1,4,9];
b = realsqrt(a)
b =
             1             2             3