addvar
              Add an input or output variable to an existing FIS structure and return the updated FIS.
The types/values of the arguments are expected to be:
| Argument | Expected Type or Value | 
|---|---|
| fis | an FIS structure | 
| in_or_out | either ’input’ or ’output’ (case-insensitive) | 
| var_name | a string | 
| var_range | a vector [x1 x2] of two real numbers | 
The vector components x1 and x2, which must also satisfy x1 <= x2, specify the lower and upper bounds of the variable’s domain.
To run the demonstration code, type "demo addvar" (without the quotation marks) at the Octave prompt.
| 
 a = newfis ('Heart-Disease-Risk', 'sugeno', ...
             'min', 'max', 'min', 'max', 'wtaver');
 a = addvar (a, 'input', 'LDL-Level', [0 300]);
 getfis (a, 'input', 1);
Name = LDL-Level
NumMFs = 0
MFLabels = 
Range = [0 300]
                     |