matlab编写方程

发布网友发布时间：2022-05-15 09:07

共1个回答

热心网友时间：2023-10-17 00:48

先求Ct-t的关系

y=dsolve('Dy-k*(24.8-y)^2=0')

y =

124/5

124/5 - 1/(25*(C1+ (k*t)/25))

再用matlab拟合参数k和C1

t=[0,1,6,12,18,24,30,36,42,48,54,60,72]';

Ct=[24.8 23.86667 23.27333 21.67333 18.48667 16.20667 13.93333...

7.70667 5.98667 4.40667 1.59333 0.66667 0]';

ft_ = fittype('124/5 - 1/(25*(C1 + (k*t)/25))',...

'dependent',{'Ct'},'independent',{'t'},...

'coefficients',{'k','C1'});

st=[-0.001 0.4]

[curve, goodness]= fit(t,Ct,ft_,'Startpoint',st)

figure,plot(t,Ct,'*'),hold on,

plot(curve,'predobs',0.99);

st =

-0.0010 0.4000

curve =

General model:

curve(t) = 124/5 - 1/(25*(C1 + (k*t)/25))

Coefficients (with 95% confidence bounds):

k = -0.001356 (-0.002203, -0.0005092)

C1 = 0.005256 (0.003034, 0.007479)

goodness =

sse: 348.0195

rsquare: 0.6773

dfe: 11

adjrsquare: 0.6480

rmse: 5.6248