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24 lines
886 B
24 lines
886 B
function val = dC_eval_dt2(C,t0)
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% Given a bernstein polynomial, evaluates its second derivative 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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val=zeros(length(t0),d);
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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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if n>2
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% val(:,j) = (n-1)*(cdiv_mat(end-1,2,:)-cdiv_mat(end-1,1,:));
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val(:,j) = (n-1)*(n-2)*(cdiv_mat(end-2,3,:)-2*cdiv_mat(end-2,2,:)+cdiv_mat(end-2,1,:));
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else
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val=0;
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end
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end
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