1. 程序一：
>> t=280:10:4000            
for i=1:length(t)                     
   if t(i)<560 & t(i)>=280
        y(i)=7*(t(i)-280)/20+99;
    elseif t(i)<1000 & t(i)>=560
        y(i)=(t(i)-560)/4+139;
    elseif t(i)<2000 & t(i)>=1000
        y(i)=(t(i)-1000)/5+199;
    elseif  t(i)>=2000
        y(i)=3*(t(i)-2000)/20+299;
  end
  end
plot(t,y)
2. 程序二：
>> t=360:10:2000
for i=1:length(t)
   if t(i)<800 & t(i)>=360
        y(i)=0.18*(t(i)-360)+68;
    elseif t(i)<1200 & t(i)>=800
        y(i)=(t(i)-800)*0.16+128;
    elseif  t(i)>=1200
        y(i)=0.13*(t(i)-1200)+188;
  end
  end
plot(t,y)