【求助】【求助】这个方程怎么解不出呢？？？？？
 

%任何
clear
clc
Uc1='Ur+exp(-1/R1/C1*t)*(-Ur+U1*exp(-td/R1/C1)-U1*exp(-td/R1/C1)*exp(-tc/R1/C1))';
Uc2='Ur+exp(-1/R2/C2*t)*(-Ur+U1*exp(-td/R2/C2)-U1*exp(-td/R2/C2)*exp(-tc/R2/C2))';
Uc3='Ur+exp(-1/R3/C3*t)*(-Ur+U1*exp(-td/R3/C3)-U1*exp(-td/R3/C3)*exp(-tc/R3/C3))';
Uc4='Ur+exp(-1/R4/C4*t)*(-Ur+U1*exp(-td/R4/C4)-U1*exp(-td/R4/C4)*exp(-tc/R4/C4))';
Uc5='Ur+exp(-1/R5/C5*t)*(-Ur+U1*exp(-td/R5/C5)-U1*exp(-td/R5/C5)*exp(-tc/R5/C5))';
Uc6='Ur+exp(-1/R6/C6*t)*(-Ur+U1*exp(-td/R6/C6)-U1*exp(-td/R6/C6)*exp(-tc/R6/C6))';
Uc7='Ur+exp(-1/R7/C7*t)*(-Ur+U1*exp(-td/R7/C7)-U1*exp(-td/R7/C7)*exp(-tc/R7/C7))';
equation1=strcat('Cg*DUr+Ur/Rg+(Ur-',Uc1,')/R1+(Ur-',Uc2,')/R2+(Ur-',Uc3,')/R3+(Ur-',Uc4,')/R4+(Ur-',Uc5,')/R5+(Ur-',Uc6,')/R6+(Ur-',Uc7,')/R7=0')
Ur=dsolve(equation1,'Ur(0)=0');
%将充电电压U0用500代之
ur=subs(Ur,500,'U1');
%将tc td等用数值带入 1.充电10秒
%ur11=subs(ur,10,'tc',5,'td');
%将tc td等用数值带入 1.充电10秒
%第1个方程
ur11=subs(ur,10,'tc');
ur12=subs(ur11,5,'td');
ur13=subs(ur12,50,'t');
uk1=0.00653;
equ1=ur13-uk1
%equ1=('ur14')
%equ1=(ur13,'=0.0653')
%equ1=subs(ur13,0.0653,'ur13');

%第2个方程
ur21=subs(ur,10,'tc');
ur22=subs(ur21,5,'td');
ur23=subs(ur22,10,'t');
uk2=0.0831;
equ2=ur23-uk2
%equ2=subs(ur23,0.0831,'Ur');

%第3个方程
ur31=subs(ur,20,'tc');
ur32=subs(ur31,10,'td');
ur33=subs(ur32,50,'t');
uk3=0.0531;
equ3=ur33-uk3
%equ3=subs(ur33,0.0531,'Ur');

%第4个方程
ur41=subs(ur,20,'tc');
ur42=subs(ur41,10,'td');
ur43=subs(ur42,10,'t');
uk4=0.0603;
equ4=ur43-uk4
%equ4=subs(ur43,0.0603,'Ur');

%第5个方程
ur51=subs(ur,50,'tc');
ur52=subs(ur51,25,'td');
ur53=subs(ur52,50,'t');
uk5=0.04923;
equ5=ur53-uk5
%equ5=subs(ur53,0.04923,'Ur');

%第6个方程
ur61=subs(ur,50,'tc');
ur62=subs(ur61,25,'td');
ur63=subs(ur62,10,'t');
uk6=0.053;
equ6=ur63-uk6
%equ6=subs(ur63,0.053,'Ur');

%第7个方程
ur71=subs(ur,100,'tc');
ur72=subs(ur71,50,'td');
ur73=subs(ur72,50,'t');
uk7=0.0353;
equ7=ur73-uk7
%equ7=subs(ur73,0.0353,'Ur');

%第8个方程
ur81=subs(ur,100,'tc');
ur82=subs(ur81,50,'td');
ur83=subs(ur82,10,'t');
uk8=0.04653;
equ8=ur83-uk8
%equ8=subs(ur83,0.04653,'Ur');

%第9个方程
ur91=subs(ur,200,'tc');
ur92=subs(ur91,100,'td');
ur93=subs(ur92,50,'t');
uk9=0.03153;
equ9=ur93-uk9
%equ9=subs(ur93,0.03153,'Ur');

%第10个方程
ur101=subs(ur,200,'tc');
ur102=subs(ur101,100,'td');
ur103=subs(ur102,10,'t');
uk10=0.0413;
equ10=ur103-uk10
%equ10=subs(ur103,0.0413,'Ur');

%第11个方程
ur111=subs(ur,500,'tc');
ur112=subs(ur111,250,'td');
ur113=subs(ur112,50,'t');
uk11=0.02653;
equ11=ur113-uk11
%equ11=subs(ur113,0.02653,'Ur');

%第12个方程
ur121=subs(ur,500,'tc');
ur122=subs(ur121,250,'td');
ur123=subs(ur122,10,'t');
uk12=0.03853;
equ12=ur123-uk12
%equ12=subs(ur123,0.03853,'Ur');

%第13个方程
ur131=subs(ur,1000,'tc');
ur132=subs(ur131,500,'td');
ur133=subs(ur132,50,'t');
uk13=0.02353;
equ13=ur133-uk13
%equ13=subs(ur133,0.02353,'Ur');

%第14个方程
ur141=subs(ur,1000,'tc');
ur142=subs(ur141,500,'td');
ur143=subs(ur142,10,'t');
uk14=0.03653;
equ14=ur143-uk14
%equ14=subs(ur143,0.03653,'Ur');

%第15个方程
ur151=subs(ur,2000,'tc');
ur152=subs(ur151,1000,'td');
ur153=subs(ur152,50,'t');
uk15=0.0153;
equ15=ur153-uk15
%equ15=subs(ur153,0.0153,'Ur');

%第16个方程
ur161=subs(ur,2000,'tc');
ur162=subs(ur161,1000,'td');
ur163=subs(ur162,10,'t');
uk16=0.01853;
equ16=ur163-uk16
%equ16=subs(ur163,0.01853,'Ur');
[R1 R2 R3 R4 R5 R6 R7 C1 C2 C3 C4 C5 C6 C7 Cg Rg]=solve(equ1,equ2,equ3,equ4,equ5,equ6,equ7,equ8,equ9,equ10,equ11,equ12,equ13,equ14,equ15,equ16,'R1,R2,R3,R4,R5,R6,R7,C1,C2,C3,C4,C5,C6,C7,Cg,Rg');