1 | function varargout = or(varargin) |
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2 | %OR (overloaded) |
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3 | % |
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4 | % z = or(x,y) |
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5 | % z = x | y |
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6 | % |
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7 | % The OR operator is implemented using the concept of nonlinear operators |
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8 | % in YALMIP. X|Y defines a new so called derived variable that can be |
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9 | % treated as any other variable in YALMIP. When SOLVESDP is issued, |
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10 | % constraints are added to the problem to model the OR operator. The new |
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11 | % constraints add constraints to ensure that z,x and y satisfy the |
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12 | % truth-table for OR. |
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13 | % |
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14 | % The model for OR is set(z>x) + set(z>y) + set(z<x+y) + set(binary(z)) |
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15 | % |
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16 | % It is assumed that x and y are binary variables (either explicitely |
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17 | % declared using BINVAR, or constrained using BINARY.) |
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18 | % |
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19 | % See also SDPVAR/AND, BINVAR, BINARY |
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20 | |
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21 | % Author Johan Löfberg |
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22 | % $Id: or.m,v 1.1 2006/08/10 18:00:21 joloef Exp $ |
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23 | |
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24 | % Author Johan Löfberg |
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25 | % $Id: or.m,v 1.1 2006/08/10 18:00:21 joloef Exp $ |
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26 | |
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27 | % Models OR using a nonlinear operator definition |
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28 | switch class(varargin{1}) |
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29 | case 'char' |
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30 | z = varargin{2}; |
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31 | x = varargin{3}; |
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32 | y = varargin{4}; |
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33 | |
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34 | % ******************************************************* |
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35 | % For *some* efficiency,we merge expressions like A|B|C|D |
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36 | xvars = getvariables(x); |
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37 | yvars = getvariables(y); |
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38 | allextvars = yalmip('extvariables'); |
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39 | |
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40 | if (length(xvars)==1) & ismembc(xvars,allextvars) |
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41 | x = expandor(x,allextvars); |
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42 | end |
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43 | |
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44 | if (length(yvars)==1) & ismembc(yvars,allextvars) |
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45 | y = expandor(y,allextvars); |
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46 | end |
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47 | % ******************************************************* |
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48 | |
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49 | xy=[x y]; |
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50 | |
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51 | varargout{1} = set(sum(xy) > z) + set(z > xy) +set(binary(z)) ; |
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52 | varargout{2} = struct('convexity','milp','monotonicity','milp','definiteness','milp'); |
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53 | varargout{3} = xy; |
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54 | |
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55 | case 'sdpvar' |
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56 | x = varargin{1}; |
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57 | y = varargin{2}; |
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58 | varargout{1} = yalmip('addextendedvariable','or',varargin{:}); |
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59 | |
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60 | otherwise |
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61 | end |
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62 | |
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63 | function x = expandor(x,allextvars) |
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64 | |
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65 | xmodel = yalmip('extstruct',getvariables(x)); |
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66 | |
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67 | if isequal(xmodel.fcn,'or') |
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68 | x1 = xmodel.arg{1}; |
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69 | x2 = xmodel.arg{2}; |
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70 | if ismembc(getvariables(xmodel.arg{1}),allextvars) |
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71 | x1 = expandor(xmodel.arg{1},allextvars); |
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72 | end |
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73 | if ismembc(getvariables(xmodel.arg{2}),allextvars) |
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74 | x2 = expandor(xmodel.arg{2},allextvars); |
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75 | end |
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76 | x = [x1 x2]; |
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77 | end |
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