...xA=0.02;yA=1.356xA^1.201;yS=1.618-0.6399exp(...

精选知识

将常数先带进去,然后再解方程组!

不过,你确定你没写错吗?你的方程中一共有E R F S xA yA xS yS xF九个变量,后面七个一直,三个方程,两个变量啊!

>> [E R F S xA yA xS yS xF]=solve('E+R=F+S','E*yA+R*xA=F*xF','E*yS+R*xS=S','xF=0.2','F=100','S=100','xA=0.02','yA=1.356*xA^1.201','yS=1.618-0.6399*exp(1.96*yA)','xS=0.067+1.43*xA^2.273')

Warning:10 equations in 9 variables.

你看,我把所有式子写在上面,求解析解时,警告：“10 equations in 9 variables.”即10个方程9个变量,方程无解,你确定你没错吗?

修改好了后给我发个消息,我再帮你解决

其他回答

这个不会，matlab学的不好

其他类似问题

问题1：解非线性方程组已知某非线性方程组如下：ff(1)=(3-5*x(1))*x(1)+1-2*x(2)＝0for k=2:9ff(k)=(3-5*x(k))*x(k)+1-x(k-1)-2*x(k+1)＝0endff(10)=(3-5*x(10))*x(10)+1-x(9)＝0试求该方程组的解.[数学科目]

function hh

X0=[0.0079 -0.0386 -0.0864 0.0466 -0.0166 -0.1171 0.0661 -0.0327 -0.1910 0.0831];

[X,FVAL,EXITFLAG]=fsolve(@myfun,X0)

function ff=myfun(x)

ff(1)=(3-5*x(1))*x(1)+1-2*x(2);

for k=2:9

ff(k)=(3-5*x(k))*x(k)+1-x(k-1)-2*x(k+1);

end

ff(10)=(3-5*x(10))*x(10)+1-x(9);

结果：

Optimization terminated:first-order optimality is less than options.TolFun.

X =

-0.3821 -0.4381 -0.4459 -0.4470 -0.4470 -0.4464 -0.4441 -0.4362 -0.4079 -0.3096

FVAL =

1.0e-007 *

0 -0.0000 -0.0000 -0.0000 -0.0001 -0.0008 -0.0073 -0.0454 -0.1214 -0.0278

EXITFLAG =

1

二次函数,好像应该还有很多组解.

问题2：求非线性方程组的“解析解”-x0*cos(b)*cos(c)-y0*(-sin(a)*cos(b)*cos(c)-cos(a)*sin(c))-z0*(-cos(a)*cos(b)*cos(c)+sin(a)*sin(c))=0 -x0*cos(b)*sin(c)-y0*(-sin(a)*cos(b)*sin(c)+cos(a)*cos(c))-z0*(-cos(a)*cos(b)*sin(c)-sin(a)*cos(c))=0 -x0*cos

程序很简单

[a,b,c]=solve('-x0*cos(b)*cos(c)-y0*(-sin(a)*cos(b)*cos(c)-cos(a)*sin(c))-z0*(-cos(a)*cos(b)*cos(c)+sin(a)*sin(c))=0','-x0*cos(b)*sin(c)-y0*(-sin(a)*cos(b)*sin(c)+cos(a)*cos(c))-z0*(-cos(a)*cos(b)*sin(c)-sin(a)*cos(c))=0','-x0*cos(b)-y0*sin(a)*cos(b)-z0*cos(a)*cos(b)=sqrt(x0^2+y0^2+z0^2)','a','b','c');

但是matlab没有解出解析解.

问题3：用牛顿迭代法解非线性方程组有两个非线性方程,未知数是x1,x2：(15x1+10x2)/[(40-30x1-10x2)^2×(15-15x1)]=5e-4;(15x1+10x2)/[(40-30x1-10x2)×(10-10x2)]=4e-2.大侠们帮帮忙,实在整不出来[数学科目]

function [r,n]=mulNewton(x0,eps)

if nargin==1

eps=1.0e-4;

end

r=x0-myf(x0)*inv(dmyf(x0));

n=1;

tol=1;

while tol>eps

x0=r;

r=x0-myf(x0)*inv(dmyf(x0));

tol=norm(r-x0);

n=n+1;

if(n>100000)

disp('迭代步数太多,方程可能不收');

return;

end

end

function f=myf(x)

x1=x(1);

x2=x(2);

f1=(15*x1+10*x2)-((40-30*x1-10*x2)^2*(15-15*x1))*5e-4;

f2=(15*x1+10*x2)-((40-30*x1-10*x2)*(10-10*x2))*4e-2;

f=[f1 f2];

function df=dmyf(x)

x1=x(1);

x2=x(2);

df=[ (3*(27*x1^2 + 12*x1*x2 - 66*x1 + x2^2 - 14*x2 + 60))/4,...

(3*x1*x2 - 3*x2 - 21*x1 + 9*x1^2 + 32)/2;(-3)*(4*x2 - 9),(-2)*(6*x1 + 4*x2 - 15)]

----------------------------------------------------------------------------------------------------------

[r,n]=mulNewton([0.2 0.6],0.001)

df =

30.9600 13.3600

19.8000 22.8000

df =

33.1741 13.7408

22.0443 24.5260

df =

35.4490 14.2583

21.4349 24.9400

df =

35.2223 14.2212

21.1843 24.7600

df =

34.9859 14.1678

21.2334 24.7120

df =

34.9828 14.1660

21.2601 24.7231

r =

0.1203 0.4785

n =

6

问题4：复杂解非线性方程组怎么解?一个多元非线性方程组,共n个方程,n个变量,f1(x1,x2,...xn)=0f2(x1,x2,...xn)=0...fn(x1,x2,...,xn)=0函数f是包含log、平方等复杂函数如何求这样方程组的解,用什么方法比较合适[数学科目]

fsolve函数

问题5：帮忙解一个非线性方程组a+b=1/2ac+bd=1/3a*c^2+b*d^2=1/4a*c^3+b*d^3=1/5a b c d分别为未知数只要答案即可这个解带入第二个方程就不对的，分子出现了根号，但是显然分子应该没有根号[数学科目]

(2)式乘(c+d):1/4+cd/2=(c+d)/3

(3)式乘(c+d):1/5+cd/3=(c+d)/4

化简后可得到c+d与cd的二元方程组.

答案是:a=(9+√6)/36

b=(9-√6)/36

c=(6+√6)/10

d=(6-√6)/10

由对称性,a,b和c,d可分别对换,形成另一组答案.

晕,我还不信改不对了