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2008057 发表于 2010-2-2 13:24

哪位高手给我看看问题出在什么地方了

function f = funzh1(a);
f1 =int(x*exp(a(1)*x),x,-3,3)/m(1)*int(exp(a(1)*x),x,-3,3);
f2 =int(x^2*exp(a(2)*x^2),x,-3,3)/m(2)*int(exp(a(2)*x^2),x,-3,3)
f3 =int(x^3*exp(a(3)*x^3),x,-3,3)/m(3)*int(exp(a(3)*x^3),x,-3,3);
f = f1.^2+f2.^2+f3.^2
%%%%%%%%%%%%%%%%%%%%%%%%%
>> m =[-0.0395 0.8244 -0.0655];
>> a0 =[-1 0 0];
>> a =lsqnonlin(funzh1,a0)
??? Input argument "x" is undefined.
Error in ==> funzh1 at 2
f1 =int(x*exp(a(1)*x),x,-3,3)/m(1)*int(exp(a(1)*x),x,-3,3);
>> a =lsqnonlin(funzh1,a0)
??? Undefined function or variable 'x'.
Error in ==> funzh1 at 2
f1 =int(x*exp(a(1)*x),x,-3,3)/m(1)*int(exp(a(1)*x),x,-3,3);

2008057 发表于 2010-2-2 14:42

请高手指教，是在不知道错在什么地方了

function f =zhfun(a)
f1 = int(x*exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3)/m(1)*int(exp(a(1)*x+a(2)*x^2 +a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3);
f2 =int(x^2*exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3)/m(2)*int(exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3);
f3 =int(x^3*exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3)/m(3)*int(exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3);
f4 = int(x^4*exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3)/m(4)*int(exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3);
f5 =int(x^5*exp(a(1)*x+a(2)*x^2 +a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3)/m(5)*int(exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3);
f =f1.^2+f2.^2+f3.^2+f4.^2+f5.^2

%%%%%%%%%%%%%%%%%%%%%%%%%%%
>> m =[-0.0395,0.8244,-0.0655,1.61858,-0.1283];
>> a0 =[-1,0,0,0,0];
>> a=lsqnonlin(zhfun,a0)
??? Input argument "x" is undefined.
Error in ==> zhfun at 2
f1 = int(x*exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3)/m(1)*int(exp(a(1)*x+a(2)*x^2 +a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3);
>> a =lsqnonlin(zhfun,a0)
??? Undefined function or variable 'x'.
Error in ==> zhfun at 2
f1 = int(x*exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3)/m(1)*int(exp(a(1)*x+a(2)*x^2 +a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3);
>> syms x
>> a =lsqnonlin(zhfun,a0)
??? Undefined function or variable 'x'.
Error in ==> zhfun at 2
f1 = int(x*exp(a(1)*x+a(2)*x^2+a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3)/m(1)*int(exp(a(1)*x+a(2)*x^2 +a(3)*x^3+a(4)*x^4+a(5)*x^5),x,-3,3);
>>

ChaChing 发表于 2010-2-2 15:42

不是跟你说"x" is undefined了?
函数中x,m是什么东西, 都没定义阿!

还有基本上两帖有点类似!? 是否使用编辑即可!

2008057 发表于 2010-2-27 13:11

matlab中的高斯牛顿法，怎么用？

我有一个非线性方程组，用fsolve求解时总是显示错误，好像是说要用高斯牛顿法求解，可是我不知道怎么用的，由于本人不懂英语，所以看帮助根本看不了，请高人指点，程序错误时这么写的：Warning: Default trust-region dogleg method of FSOLVE cannot
handle non-square systems; switching to Gauss-Newton method.
> In fsolve at 232
Conditioning of Gradient Poor - Switching To LM method
Optimization terminated: directional derivative along
search direction less than TolFun and infinity-norm of
gradient less than 10*(TolFun+TolX).

2008057 发表于 2010-2-27 19:57

matlab积分问题

“x*exp(ax+bx2+cx3)在特定区间内的积分怎么求啊，应该用哪个函数，我试过fsolve /cumtrapz/trapz都出错，怎么办啊，其中x2表示x 的平方，x3为立方请高手指点下

bleakhand 发表于 2010-3-1 13:10

原帖由 2008057 于 2010-2-27 19:57 发表 http://www.chinavib.com/forum/images/common/back.gif
“x*exp(ax+bx2+cx3)在特定区间内的积分怎么求啊，应该用哪个函数，我试过fsolve /cumtrapz/trapz都出错，怎么办啊，其中x2表示x 的平方，x3为立方请高手指点下

int(x*exp(a*x+b*x^2+c*x^3),0,100)
%内积分

2008057 发表于 2010-3-1 14:56

谢谢，可是还有错误

谢谢回复，这个试过了，总是显示如下错误，不知道什么原因
>> syms a b c x
>> int(x*exp(a*x+b*x^2+c*x^3),-0.1,0.1)
Warning: Explicit integral could not be found.
> In sym.int at 58

ans =

int(x*exp(a*x+b*x^2+c*x^3),x = -1/10 .. 1/10)

sobolev 发表于 2010-3-1 21:27

找一本matlab数学实验相关的书籍，上面应该有详细的介绍:@)

2008057 发表于 2010-3-2 11:32

回复板凳 ChaChing 的帖子

这个不只是x未定义的问题，定义之后还是有错误，下一个错误提示能帮我分析下吗，好像是M文件的第二行有错，是不是表达式不对呀，还是用的函数有错误

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