nearst_16006524.m

根据所给样本数据用三种不同的方法绘制该公路并估计其长度。 分别用线性插值法、最近邻域插值法和三次样条插值法计算公路长度

x=[0,30,50,70,80,90,120,148,170,180,202,212,230,248,268,271,280,290,300,312,320,340,360,372,382,390,416,430,478];
y=[80 64 47 42 48 66 80 120 121 138 160 182 200 208 212 210 200 196 188 186 200 184 188 200 202 240 246 280 296];
x1=[200 240 280 314 320 340 360 380 420 440 478];
y1=[400 390 392 360 356 346 334 328 334 308 296];
xi1=1:478;
xi2=200:478;
yi1=interp1(x,y,xi1,'nearst');
yi2=interp1(x1,y1,xi2,'nearst');
plot(xi1,yi1,'-');
hold on;
plot(xi2,yi2,'-');
for i=1:477;
    a1=xi1(i+1);
    a2=xi1(i);
    b1=yi1(i+1);
    b2=yi1(i);
    l1(i)=sqrt((a1-a2)^2+(b1-b2)^2);
end;
L1(479)=0;
L1(1)=0;
for n1=1:477;
    L1(n1+1)=L1(n1)+l1(n1);
end;
L1(478);
for i=1:278;
    c1=xi2(i+1);
    c2=xi2(i);
    d1=yi2(i+1);
    d2=yi2(i);
    l2(i)=sqrt((c1-c2)^2+(d1-d2)^2);
end;
L2(280)=0;
L2(1)=0;
for n2=1:278;
    L2(n2+1)=L2(n2)+l2(n2);
end;
L=L1(478)+L2(279);
L