basicfun.m

malab语言实现bspline曲线拟合

function w = basicfun(n,p,t,u)

% 由T和U计算N

for i = 1:n+p+1
    if u(i)<=t & t<=u(i+1)
      N(i)=1;
    else
      N(i)=0;
    end
end
for j = 1:p
    for i=1:n+p-j+1
        if u(i)<=t & t<=u(i+j+1)
            if  u(i+j)-u(i)==0 & u(i+j+1)-u(i+1)~=0
                N(i)=((u(i+j+1)-t)*N(i+1))/(u(i+j+1)-u(i+1));
            elseif  u(i+j+1)-u(i+1)==0 &  u(i+j)-u(i)~=0
                N(i)=((t-u(i))*N(i))/(u(i+j)-u(i));
            elseif u(i+j)-u(i)~=0 & u(i+j+1)-u(i+1)~=0
                N(i)=((t-u(i))*N(i))/(u(i+j)-u(i))+((u(i+j+1)-t)*N(i+1))/(u(i+j+1)-u(i+1));   
            else 
                N(i)=0; 
            end
        else
            N(i)=0;
        end
    end
end
w = N(1:n+1);