opImag.m

classdef opImag < opSpot
%OPIMAG   Complex imaginary part of operator.
%
%   opImag(OP) is the complex imaginary part of operator OP. Note
%   that the resulting operator is real.
%
%   See also opConj, opReal.

%   Copyright 2009, Ewout van den Berg and Michael P. Friedlander
%   See the file COPYING.txt for full copyright information.
%   Use the command 'spot.gpl' to locate this file.

%   http://www.cs.ubc.ca/labs/scl/spot

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    % Methods
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    methods

       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
       % Constructor
       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
       function op = opImag(A)
          
          if nargin ~= 1
             error('Exactly one operator must be specified.')
          end
           
          % Input matrices are immediately cast as opMatrix's.
          if isa(A,'numeric'), A = opMatrix(A); end
          
          % Check that the input operators are valid.
          if ~isa(A,'opSpot')
             error('Input operator is not valid.')
          end
          
          % Construct operator
          [m, n] = size(A);
          op = op@opSpot('Imag', m, n);
          op.cflag      = false;
          op.linear     = A.linear;
          op.sweepflag  = A.sweepflag;
          op.children   = {A};
       end % Constructor
      
       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
       % Display
       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
       function str = char(op)
          op1 = op.children{1};
          str = ['Imag(', char(op1), ')'];
       end % Char
       
    end % Methods

    methods ( Access = protected )
       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
       % Multiply
       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
       function y = multiply(op,x,mode)
          opA = op.children{1};
          if mode == 1
             if isreal(x)
                % Purely real
                y = imag(applyMultiply(opA,x,mode));
             elseif isreal(sqrt(-1)*x)
                % Purely imaginary
                y = imag(applyMultiply(opA,imag(x),mode)) * sqrt(-1);
             else
                % Mixed
                y = imag(applyMultiply(opA,real(x),mode)) + ...
                    imag(applyMultiply(opA,imag(x),mode)) * sqrt(-1);
             end
          else
             if isreal(x)
                % Purely real
                y = imag(applyMultiply(opA,x,mode)) * -1;
             elseif isreal(sqrt(-1)*x)
                % Purely imaginary
                y = imag(applyMultiply(opA,imag(x),mode)) * sqrt(-1) * -1;
             else
                % Mixed
                y = imag(applyMultiply(opA,real(x),mode)) * -1 + ...
                    imag(applyMultiply(opA,imag(x),mode)) * sqrt(-1) * -1;
             end
          end
       end % Multiply

    end % Methods
   
end % Classdef