y=25000./(1+exp(B).*exp(A*x)); A,B均為所求出的數(shù)值,如何對他在0-60上求定積分函數(shù)源碼如下
function [E,N]=euler(a,b,ya)
a=0;b=60;ya=250;
h=0.2;s=0;
M=(b-a)/h;
T=zeros(1,M+1);
Y=zeros(1,M+1);
T=a:h:b;
Y(1)=ya;
A=0;
B=0;
for j=1:M
Y(j+1)=Y(j)+h*f(Y(j));
end
E=[T' Y'];
for j=1:M
plot(T(j),Y(j),'r*');
s=s+Y(j);
hold on;
end
N=s/60
G=log(25000*Y.^(-1)-1);
xmean=mean(T);
ymean=mean(G);
sumx2=(T-xmean)*(T-xmean)';
sumxy=(G-ymean)*(T-xmean)';
A=sumxy/sumx2;
B=ymean-A*xmean;
hold on;
x=0:0.1:60;
y=25000./(1+exp(B).*exp(A*x));
plot(x,y)
quad(y,0,60)
function dy=f(y)
dy=0.00003*y*(25000-y);