关于fsolve函数的用法

2008057

function g =funmy11(a)
fa1 = @(x)x.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3);
fa2 = @(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3);
f1 =quadl(fa1,50.45,50.57)/quadl(fa2,50.45,50.57)-50.5295;
fb1 [email==@(x)x.^2.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]=@(x)x.^2.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
fb2 [email==@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]=@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
f2 =quadl(fb1,50.45,50.57)/quadl(fb2,50.45,50.57)-2.5532e+003;
fc1 [email==@(x)x.^3.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]=@(x)x.^3.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
fc2 [email==@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]=@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
f3 =quadl(fc1,50.45,50.57)/quadl(fc2,50.45,50.57)-1.2901e+005;
g =[f1;f2;f3];
%%%%%%%%%%%%%%%%%%%
a0=[1,1,0];
options =optimset('Display','off');
[a,fval] =fsolve(@funmy11,a0,options)

Warning: Infinite or Not-a-Number function value encountered.
> In quadl at 101
  In funmy11 at 4
  In fsolve at 180
  In aac at 3
Warning: Infinite or Not-a-Number function value encountered.
> In quadl at 101
  In funmy11 at 7
  In fsolve at 180
  In aac at 3
Warning: Infinite or Not-a-Number function value encountered.
> In quadl at 101
  In funmy11 at 10
  In fsolve at 180
  In aac at 3
...

a =
     1     1     0

fval =
   NaN
   NaN
   NaN
>>  请高手帮忙看下，什么问题啊，我看不明白，用这个方法解别的问题可以，但是只要一换数就不行了，数太大或太小都不能求解，我该怎么设置参数呢，请指教

[ 本帖最后由 ChaChing 于 2010-3-11 11:32 编辑 ]

2008057

function g =funp1(a);
[email=fa1=@(x)x.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]fa1=@(x)x.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
[email=fa2=@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]fa2=@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
f1 =quad(fa1,-0.025,-0.026)/quad(fa2,-0.025,-0.026)+0.0257;
fb1 [email==@(x)x.^2.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]=@(x)x.^2.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
fb2 [email==@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]=@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
f2 =quad(fb1,-0.025,-0.026)/quad(fb2,-0.025,-0.026)-0.00066058;
[email=fc1=@(x)x.^3.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]fc1=@(x)x.^3.*exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
fc2 [email==@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3]=@(x)exp(a(1).*x+a(2).*x.^2+a(3).*x.^3[/email]);
f3 =quad(fc1,-0.025,-0.026)/quad(fc2,-0.025,-0.026)+0.00001698;
g =[f1;f2;f3];


a0 =[-0.1,0.1,0];
options =optimset('Display','iter','MaxFunEvals',400);
[a,fval] = fsolve(@funp1,a0,options)
Optimization terminated: first-order optimality is less than options.TolFun.
a =
     0     0     0

fval =
  1.0e-003 *
    0.2000
   -0.0102
    0.0004

elitecn

我在百度知道经常发现有些提问者，他们希望别人花很多时间和精力帮他们解答问题，可是自己却懒得多打几个字把提的问题稍微详细描述下。

2008057

问题已经很清楚了，程序都在，怎么说我描述不够详细呢，还是您懒得看呢