buyuplot.m

捕鱼问题源代码

close all;
clc;clear;
f=inline('(17.86*0.42*k*(1-exp(-(0.8+0.42*k)*2/3))/(0.8+0.42*k)+exp(-0.8-0.42*2*k/3)*22.99*k*(1-exp(-(0.8+k)*2/3))/(1-exp(-0.8-2*k/3))/(0.8+k))*1.22e11*exp(-1.6)/(1+1/(1.109e5*(0.5+1/(exp(0.8+2*k/3)-1))*exp(-(6.4+0.42*2*k)/3)-1))','k')
figure(1);
ezplot(f,[-5,40]);
axis([0 35 0 4e11]);
xlabel('捕捞强度系数');
ylabel('年捕捞量');
title('可持续捕捞年捕捞量与捕捞强度系数的关系');
text(13,3.7e11,'(17.3629,3.8871\times10^{11})');

hold on;
plot(17.3629,3.8871e11,'.k');

hold off;
E=zeros(1,12);
W=zeros(1,12);
time=4:1:15;

for len=4:1:15
    k=[0:0.1:15.9,16:0.0001:18,18.1:0.1:35];
    m=length(k);
    r=0.8;
    n=zeros(1,len+1);
    N1=[1.22e11,zeros(1,len)];
    N2=[2.97e10,zeros(1,len)];
    N3=[1.01e10,zeros(1,len)];
    N4=[3.29e9,zeros(1,len)];
    f=zeros(1,m);
    for j=1:m
        for i=1:len
            n(i+1)=0.5*1.109e5*N3(i)*exp(-(0.42*k(j)+r)*2/3)+1.109e5*N4(i)*exp(-(k(j)+r)*2/3);
            N1(i+1)=(1.22e11*n(i+1))/(1.22e11+n(i+1));
            N2(i+1)=exp(-r)*N1(i);
            N3(i+1)=exp(-r)*N2(i);
            N4(i+1)=N3(i)*exp(-(0.42*k(j)*2/3+r))+N4(i)*exp(-(k(j)*2/3+r));
            f(j)=f(j)+17.86*N3(i)*0.42*k(j)*(1-exp(-(r+0.42*k(j))*2/3))/(r+0.42*k(j))+22.99*N4(i)*k(j)*(1-exp(-(r+k(j))*2/3))/(r+k(j));
        end
    end
    [W(len-3),pos]=max(f);
    E(len-3)=k(pos);
end
E
figure(2);
plot(time,E);axis([4 15 16.5 18.5]);
xlabel('连续捕捞年数');
ylabel('最佳捕捞强度');
title('最佳捕捞强度与连续捕捞年数关系曲线');
E=17.3629*ones(size(time));
hold on;
plot(time,E,'--r');
text(7,17.2,'可持续捕捞最佳捕捞强度系数');