Programming and Data Types

The Polynom Constructor Method

Here is the polynom class constructor, @polynom/polynom.m.

• function p = polynom(a)
  %POLYNOM Polynomial class constructor.
  %   p = POLYNOM(v) creates a polynomial object from the vector v,
  %   containing the coefficients of descending powers of x.
  if nargin == 0
     p.c = [];
     p = class(p,'polynom');
  elseif isa(a,'polynom')
     p = a;
  else
     p.c = a(:).';
     p = class(p,'polynom');
  end
  

Constructor Calling Syntax

You can call the polynom constructor method with one of three different arguments:

• No Input Argument - If you call the constructor function with no arguments, it returns a polynom object with empty fields.
• Input Argument is an Object - If you call the constructor function with an input argument that is already a polynom object, MATLAB returns the input argument. The isa function (pronounced "is a") checks for this situation.
• Input Argument is a coefficient vector - If the input argument is a variable that is not a polynom object, reshape it to be a row vector and assign it to the .c field of the object's structure. The class function creates the polynom object, which is then returned by the constructor.

An example use of the polynom constructor is the statement

• p = polynom([1 0 -2 -5])
  

This creates a polynomial with the specified coefficients.

Example -- A Polynomial Class

Converter Methods for the Polynom Class