ninetiger 发表于 2009-5-4 11:05

求助:本人在用MATLAB求解方程组时遇到困难,不知道怎么办,求高手帮帮忙,先谢了

我想求下列方程组:
352.1775*exp(a+b*x)+190.6011*exp(a+b*x+c*x^2)+182.2338*exp(a+b*x+c*x^2+d*x^3)+218.8316*exp(a+b*x+c*x^2+d*x^3+e*x^4)+153.3209*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)=219.4330


(2.2244e+003)*exp(a+b*x)+(1.1209e+003)*exp(a+b*x+c*x^2)+(1.0560e+003)*exp(a+b*x+c*x^2+d*x^3)+(1.5519e+003)*exp(a+b*x+c*x^2+d*x^3+e*x^4)+772.1131*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)=1.3451e+003


(1.5032e+004)*exp(a+b*x)+(7.2996e+003)*exp(a+b*x+c*x^2)+(6.8595e+003)*exp(a+b*x+c*x^2+d*x^3)+(1.1602e+004)*exp(a+b*x+c*x^2+d*x^3+e*x^4)+(4.5451e+003)*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)=9.0677e+003


(1.0683e+005)*exp(a+b*x)+(5.0680e+004)*exp(a+b*x+c*x^2)+(4.7699e+004)*exp(a+b*x+c*x^2+d*x^3)+(8.9489e+004)*exp(a+b*x+c*x^2+d*x^3+e*x^4)+()2.9292e+004*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)=6.4798e+004


(7.8776e+005)*exp(a+b*x)+(3.6764e+005)*exp(a+b*x+c*x^2)+(3.4708e+005)*exp(a+b*x+c*x^2+d*x^3)+(7.0525e+005)*exp(a+b*x+c*x^2+d*x^3+e*x^4)+(2.0036e+005)*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)=4.8162e+005


a=-log(int(exp(b*x+c*x^2+d*x^3+e*x^4+f*x^5),x,0,9))


exp(a+b*x)+exp(a+b*x+c*x^2)+exp(a+b*x+c*x^2+d*x^3)+exp(a+b*x+c*x^2+d*x^3+e*x^4)+exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)=1


其中x的范围是,a,b,c,d,e,f都是未知量。


我的编程是:
clear;
syms a b c d e f x
s1=352.1775*exp(a+b*x)+190.6011*exp(a+b*x+c*x^2)+182.2338*exp(a+b*x+c*x^2+d*x^3)+218.8316*exp(a+b*x+c*x^2+d*x^3+e*x^4)+153.3209*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)-219.4330;
s2=(2.2244e+003)*exp(a+b*x)+(1.1209e+003)*exp(a+b*x+c*x^2)+(1.0560e+003)*exp(a+b*x+c*x^2+d*x^3)+(1.5519e+003)*exp(a+b*x+c*x^2+d*x^3+e*x^4)+772.1131*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)-1.3451e+003;
s3=(1.5032e+004)*exp(a+b*x)+(7.2996e+003)*exp(a+b*x+c*x^2)+(6.8595e+003)*exp(a+b*x+c*x^2+d*x^3)+(1.1602e+004)*exp(a+b*x+c*x^2+d*x^3+e*x^4)+(4.5451e+003)*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)-9.0677e+003;
s4=(1.0683e+005)*exp(a+b*x)+(5.0680e+004)*exp(a+b*x+c*x^2)+(4.7699e+004)*exp(a+b*x+c*x^2+d*x^3)+(8.9489e+004)*exp(a+b*x+c*x^2+d*x^3+e*x^4)+(2.9292e+004)*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)-6.4798e+004;
s5=(7.8776e+005)*exp(a+b*x)+(3.6764e+005)*exp(a+b*x+c*x^2)+(3.4708e+005)*exp(a+b*x+c*x^2+d*x^3)+(7.0525e+005)*exp(a+b*x+c*x^2+d*x^3+e*x^4)+(2.0036e+005)*exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)-4.8162e+005;
s6=a+log(int(exp(b*x+c*x^2+d*x^3+e*x^4+f*x^5),x,0,9));
s7=exp(a+b*x)+exp(a+b*x+c*x^2)+exp(a+b*x+c*x^2+d*x^3)+exp(a+b*x+c*x^2+d*x^3+e*x^4)+exp(a+b*x+c*x^2+d*x^3+e*x^4+f*x^5)-1;
solve(s1,s2,s3,s4,s5,s6,s7)


错误提示是:
Warning: Explicit integral could not be found.
> In sym.int at 58
In aaa at 8
??? Error using ==> solve at 134
Error, (in evalf/int) invalid arguments
Error in ==> sym.solve at 49
= solve(S{:});
Error in ==> aaa at 10
solve(s1,s2,s3,s4,s5,s6,s7)


请各位高手帮帮忙,怎样才能求出来a,b,c,d,e,f。劳烦了~~~
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