35 lines
1.2 KiB
35 lines
1.2 KiB
function val = dCR_eval_dt(C,t0)
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% Given a bernstein polynomial, evaluates it i at t0;
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% Input parameters
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% C: This is a bernstein polynomial's control points (aka coefficients)
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% t0: This is the point at which we wish to split the polynomial
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% Output parameters
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% val: row vector of values of the bernstein polynomial defined by C at t0
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t0=reshape(t0,1,1,length(t0));
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[d,n] = size(C);
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d=d-1;
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val=zeros(length(t0),d);
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cwv_mat=zeros(n,n,length(t0));
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cwv_mat(1,:,:)=repmat(C(d+1,:),1,1,length(t0));
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wv=dC_eval(C(d+1,:),t0);
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wdv=dC_eval_dt(C(d+1,:),t0);
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nv=dC_eval(C(1:2,:),t0);
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ndv=dC_eval_dt(C(1:2,:),t0);
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val=(wv.*ndv-wdv.*nv)./(wv.^2);
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% for i=2:n
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% cwv_mat(i,:,:)=cwv_mat(i-1,:,:).*(1-t0) + circshift(cwv_mat(i-1,:,:),-1,2).*t0;
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% end
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% for j=1:d
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% cdiv_mat=zeros(n,n,length(t0));
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% cdiv_mat(1,:,:)=repmat(C(j,:),1,1,length(t0));
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% for i=2:n
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% cdiv_mat(i,:,:)=cdiv_mat(i-1,:,:).*(1-t0) + circshift(cdiv_mat(i-1,:,:),-1,2).*t0;
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% end
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% % cdiv_mat=triu(fliplr(cdiv_mat));
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% % ptmat=cdiv_mat./cwv_mat;
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%
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% val(:,j) = (n-1)*(cdiv_mat(end-1,2,:)./cwv_mat(end-1,2,:)-cdiv_mat(end-1,1,:)./cwv_mat(end-1,1,:));
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% end
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% wt= (cwv_mat(end-1,2,:).*cwv_mat(end-1,1,:))./(cwv_mat(end,1,:).^2);
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% val=(val).*reshape(wt,length(t0),1);
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end
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