2005高教社杯全国大学生数学建模竞赛论文长江水质的评价和预测

function zohn2

X=[174,179,183,189,207,234,220.5,256,270,285]; x=[174,179,183,189,207,234,220.5,256,270,285]; Y=[174,179,183,189,207,234,220.5,256,270,285]; y=[]; Z=[]; z=[]; r=[];

for i=2:10

X(i)=X(i)+X(i-1); end

for j=2:10

Z(j)=0.5*X(j)+0.5*X(j-1); end

Z(1)=[]; Y(1)=[];

B=[-Z;ones(1,9)]'; C=inv(B'*B)*B'*Y'; a=C(1); b=C(2); for k=1:19

y(k+1)=(174-b/a)*exp(-a*k)+b/a; end

y(1)=174; for t=1:19

z(t+1)=y(t+1)-y(t); end

z(1)=174;

s=[1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014]; plot(s,z,'r'); z

以上是对单个城市一个月的求解程序，如果城市改变，仅需要改变输入的X，x，Y值即可。

附录三

function zohn33

A=[5.18 4.85 5.35 4.04 6.2 9.23 7.77 7.17 0.88 5.83 5.17 5.55 5.06 5.54 4.88 4.97 9.18 7.36 9.3 7.2 6.65 6.18 6.18 4.79 4.4 3.38 3.87 3.39 ];

B=[1.1 1 1.7 0.77 1.8 3 2.6 3.1 9 1.5 1.9 0.6 0.8 0.4 2.7 3.4 2 7.1 4.3 4.5 1.8 .7 0.5 1.7 1.6 2.2 2.2 1.1 ];

C=[0.92 1.01 2.18 3.06 6.5 12.9 14 14.5 4.2 2.09 0.73 1.48 2.53 1.19 1.62 0.63 7.05 5.37 11.3 6.02 3.01 0.99 0.72 1.18 1.18 0.97 0.92 ];

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a=[]; b=[]; c=[]; s=[]; x=[];

for i=1:28

if A(i)<=14.4&7.5

for j=1:28

if B(j)<2&B(j)>=0, b(j)=B(j)/2+1; elseif B(j)<4&B(j)>=2, b(j)=(B(j)-2)/2+2; elseif B(j)<6&B(j)>=4, b(j)=(B(j)-4)/2+3; elseif B(j)<10&B(j)>=6, b(j)=(B(j)-6)/4+4; end end b;

for k=1:28

if C(k)<=0.15&C(k)>0, c(k)=C(k)/0.15+1;

elseif C(k)<=0.5&C(k)>0.15, c(k)=(C(k)-0.15)/0.35+2; elseif C(k)<=1&C(k)>0.5, c(k)=(C(k)-0.5)/0.5+3; elseif C(k)<=1.5&C(k)>1, c(k)=(C(k)-1)/0.5+4; elseif C(k)<=2&C(k)>1.5, c(k)=(C(k)-1.5)/0.5+5;

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elseif C(k)<=24.2&C(k)>2, c(k)=(C(k)-2)/22.2+6; end end c;

for t=1:28

s(t)=1/3*(a(t)+b(t)+c(t)); end

mean(s); mean(a); mean(b); mean(c); w=1:28;

subplot(4,1,1); plot(w,a,'r'); subplot(4,1,2); plot(w,b,'b'); subplot(4,1,3); plot(w,c,'m'); subplot(4,1,4); plot(w,s,'g');

不同情况对应不同输入数据。

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