ocset(varargin)

function sys = ocset(varargin)
%OCSET Create/alter OCCDS data structure.
%   SYS = OCSET('PARAM1',VALUE1,'PARAM2',VALUE2,...) creates a data
%   structure SYS in which the named parameters have the specified values.
%   Any unspecified parameters are set to the default value for that 
%   parameter. 
%
%   SYS = OCSET(OLDSYS,'PARAM1',VALUE1,...) creates a copy of OLDSYS
%   with the named parameters altered with the specified values.
%
%   SYS = OCSET(OLDSYS,NEWSYS) combines an existing options structure
%   OLDSYS with a new options structure NEWSYS.  Any parameters in NEWSYS
%   with non-empty values overwrite the corresponding old parameters in
%   OLDSYS.
%
%   SYS = OCSET (with no input arguments) creates an options structure
%   SYS where all the fields are set to the default.
%
%
%OCSET PARAMETERS for MATLAB
%		Type - Indicates combination of open-closed PD controls
%				0: No control
%				1: open-closed P
%				2: open-closed PD (default)
%				3: open-closed D
%				4: closed P
%				5: closed PD
%				6: closed D
%				7: open-only
%		Alpha - Structural value (default 10)
%		Gamma - Damping constant (default 0.01)
%       L - Length of beam (default 1)
%		xo - Initial modal displacement vector (default 0)
%		vo - Initial modal velocity vector (default 1)
%		a - open loop parameter (default 0)
%		b - open loop parameter (default 0)
%		cp - closed loop P parameter (default 100)
%		cd - closed loop D parameter (default 10)
%		To - Terminal time (default 0.01)
%		uu - Performance weight vector (default [1 1 1e-6 1e-6 1e-6])
%		Ti - Initial time (default 0)
%		IOL - Independent open loop control indicator 
%			0: Dependent (default)
%			1: Independent
%		T - Length of time delay (default 0)
%
%   Note: To see OCSET parameters for the OPTIMIZATION TOOLBOX
%         (if you have the Optimization Toolbox installed), type
%             help optimoptions
%
%   Examples
%     To create options with the default options for fzero
%       options = optimset('fzero');
%     To create an options structure with TolFun equal to 1e-3
%       options = optimset('TolFun',1e-3);
%     To change the Display value of options to 'iter'
%       options = optimset(options,'Display','iter');
%

if nargin>0 && isstruct(varargin{1})
    % Use specified system
    sys = varargin{1};
    varargin = varargin(2:end);
else
    % Create default system
    sys=struct('Type',2,'Alpha',10,'Gamma',0.01,'xo',0,'vo',1,'a',0,'b',0,'cp',100,...
        'cd',10,'To',0.01,'uu',[1 1 1e-6 1e-6 1e-6],'Ti',0,'IOL',0,'T',0,'L',1);    
end
if nargin>1 && isstruct(varargin{1})
    % Combine old with new
    newsys = varargin{1};
    flds = fieldnames(newsys);
    vals = struct2cell(newsys);
    for n=1:length(flds)
        sys=setfield(sys,flds{n},vals{n});
    end        
elseif ~isempty(varargin) && mod(length(varargin),2)==0
    for n = 1:2:length(varargin)-1
        sys=setfield(sys,varargin{n},varargin{n+1});
    end   
end
%  % Ensure column vector
% sys.a = sys.a(:);
% sys.b = sys.b(:);
%  % Ensure row vector
% sys.xo = sys.vo(:).';
% sys.vo = sys.xo(:).';