How to solve equation with "Error using symengine A square matrix is expected",

26 次查看（过去 30 天）

显示更早的评论

friet 2017-4-8

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/334373-how-to-solve-equation-with-error-using-symengine-a-square-matrix-is-expected

评论： friet 2017-4-8

采纳的回答： Walter Roberson

在 MATLAB Online 中打开

Hello

My code below written to solve an equation works well with a single input parameter d (line 8). However, when I have a vector for the input "d" as shown in line 9, Matlab complain that I have "symengine". here is my code.Any help is appreciated.

clear all
clc
close all
% definition of constants
Y=9*10^(-13);       
%  d=20*10^-3;   
  d= linspace(1*10^-3,20*10^-3,10);             
q=1.6*10^(-19);            
kB=4.0434e-21;            
er=2.8320e-11;
mp=1*10^-9;                
mn=1*10^-9;                
c=3.2520e+23;
kr=q*(mp+mn)/(er);
no=Y/(q*(mp+mn));
kdo=kr*no*no/c;
Lb= (q^2)/(8*pi*er*kB);
syms Vs
b=(Lb*q*(Vs./d))./(kB );
num=besselj(1,sqrt(-8*b));
den=sqrt(-2*b);
Fb=num./den;
kd=kdo*Fb;
eqn = (((kd*kr*c)^0.5).*d.^2)./(mp+mn)==Vs;
solVs = solve(eqn,Vs);
vpa(solVs)

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Walter Roberson 2017-4-8

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/334373-how-to-solve-equation-with-error-using-symengine-a-square-matrix-is-expected#answer_262320

在 MATLAB Online 中打开

eqn = (((kd*kr*c).^0.5).*d.^2)./(mp+mn)==Vs;

Notice the .^ instead of ^

5 个评论
显示 3更早的评论隐藏 3更早的评论

Walter Roberson 2017-4-8

在 MATLAB Online 中打开

temp = arrayfun( @vpasolve, eqn, 'Uniform', 0);
solVs = horzcat( temp{:} );

friet 2017-4-8

Thanks!

请先登录，再进行评论。

类别

Mathematics and Optimization Symbolic Math Toolbox Mathematics Number Theory

在 Help Center 和 File Exchange 中查找有关 Number Theory 的更多信息

Community Treasure Hunt

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

Start Hunting!

Translated by