109 lines
2.4 KiB
Mathematica
109 lines
2.4 KiB
Mathematica
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function deg=degree(p,y,flag,vector)
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%DEGREE Polynomial degree
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%
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% DEG = DEGREE(p,x,flag,vector)
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%
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% p : SDPVAR object.
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% x : Degree w.r.t linear SDPVAR objects.
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% flag : 'max', 'min'. Default 'max'
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% vector : If vector = 1, returns degree of each element in p
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%
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% Examples
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% x1 = sdpvar(1,1);x2 = sdpvar(1,1);
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% p = [x1;x1*x2+x2^2];
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%
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% degree(p) returns 2
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%
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% degree(p,x1) returns 1
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%
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% degree(p,[x1 x2]) returns [1 2]
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%
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% degree(p,[x1 x2],[],1) returns [1 0;1 2]
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%
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% degree(p,[],1) returns [1;2]
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if nargin == 3
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if isa(flag,'double')
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% Old syntax
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deg = degree(p,y,'max',flag);
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return;
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end
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end
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if isnumeric(p)
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if nargin==1
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deg = 0;
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else
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deg = zeros(1,length(y));
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end
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return
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end
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if nargin<2 || isempty(y)
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y = recover(depends(p));
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end
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if nargin < 3
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flag = 'max';
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end
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if nargin < 4
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vector = 0;
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end
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if vector == 0
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exponent_p = exponents(p,y);
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switch nargin
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case 1
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degrees = sum(exponent_p,2);
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deg = full(max(degrees));
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case {2,3}
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switch flag
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case 'max'
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deg = full(max(exponent_p,[],1));
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case 'min'
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deg = full(min(exponent_p,[],1));
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otherwise
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end
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otherwise
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error('Too many arguments. Wadda ya mean?')
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end
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else
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p = p(:);
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if isempty(y)
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yy = recover(depends(p));
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else
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yy = y;
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end
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deg = zeros(length(p),length(depends(yy)));
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for i = 1:length(p)
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z.type = '()';
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z.subs{1} = i;
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pi = subsref(p,z);
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if isnumeric(pi)
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deg(i,:) = 0;
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else
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exponent_p = exponents(pi,yy);
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switch nargin
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case 1
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deg(i,:) = full(max(sum(exponent_p,2)));
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case {2,3,4}
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switch flag
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case 'max'
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deg(i,:) = full(max(exponent_p,[],1));
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case 'min'
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deg(i,:) = full(min(exponent_p,[],1));
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otherwise
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error('Do not understand the flag')
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end
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otherwise
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error('Too many arguments. Wadda ya mean?')
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end
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end
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end
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if isempty(y)
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deg = sum(deg,2);
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end
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end
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