清空筛选条件
清空筛选条件

Error in assigning value to variable while solving non-linear equations using syms

1 次查看（过去 30 天）
GAGANDEEP KAUR
GAGANDEEP KAUR 2021-2-16
I am trying to solve some non-linear equations. While running I am getting error as follows. May I please know what exactly this error means( as I need min positive value from all the solutions) and it can be resolved
Unable to perform assignment because the left and right sides have a different number of elements.
Error in SpeciationCal (line 29)
n(i)=min(S.b)
syms a b c
x3=[0.000804557 0.038813753 0.109515494 0.258253623 0.250365943 0.266695352 0.254064153 0.355464596 0.367390937 0.367899743];
x1=[0.812965986 0.75197909 0.647030256 0.315659359 0.381316826 0.324185571 0.385450182 0.198472313 0.161364552 0.181784492];
x2=[0.186229457 0.209207157 0.243454249 0.426087018 0.368317231 0.409119077 0.360485665 0.446063091 0.47124451 0.450315765];
T=[384.2 392.1 396.4 392 406.1 405 409.6 416.2 416.4 417.1];
N=length(x1);
K1=zeros(N,1);K2=zeros(N,1);K3=zeros(N,1);m=zeros(N,1);n=zeros(N,1);o=zeros(N,1);
for i=1:N
K1(i)=exp((-936.28)+((40216.27)/T(i))+(151.983*(log(T(i))))+(-0.1675*(T(i))))
K2(i)=exp((1044.78)+(-45171.42/T(i))+(-165.20*log(T(i))+(0.1511*(T(i)))))
K3(i)=exp((-228.838)+(12587.48/T(i))+(40.68593*log(T(i)))+(-0.09838*(T(i))))
eqns=[((a*(a-b))/((x1(i)-a-c+3*b)*(x2(i)-a-c)))==K1(i),((b*3*b)/(a-b)*(x3(i)-b))==K2(i),((c*c)/((x1(i)-a-c+3*b)*(x2(i)-a-c)))==K3(i)]
S=vpasolve(eqns,[a,b,c])
warning('off', 'symbolic:numeric:NumericalInstability')
S.a(S.a<0)=[];
S.b(S.b<0)=[];
S.c(S.c<0)=[];
idxa= abs(imag(S.a)) < eps;
idxb = abs(imag(S.b)) < eps;
idxc = abs(imag(S.c)) < eps;
S.a = S.a(idxa);
S.b = S.b(idxb);
S.c = S.c(idxc);
m(i)=min(S.a)
n(i)=min(S.b)
o(i)=min(S.c)
end

请先登录，再回答此问题。

回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Symbolic Math Toolbox 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by