As i using function "solve", matlab give me an error.

here is my code clear all, close all, clc;

x=sym('x',[3,1]); syms u; syms a ru R b;

% % % ************

a=10; b=100/7; ru=2*x(1)^3/7-8*x(1)/7; R=0; g=[0;1;0]; uh=0;

% % % ************

f=[a*(x(2)-x(1)-ru);x(1)-x(2)+x(3);-b*x(2)-R*x(3)]; xd=f+g*u; matlabFunction(xd,'File','CHUAcircuit');

% % % ************ % % EX.1 % 1.1 % u=sym('u',[3,1]); % eqns=[xd,u] [xh1,xh2,xh3]=solve(eqns,[x,u])

and here's the error: Error using sym.getEqnsVars>checkVariables (line 92) The second argument must be a vector of symbolic variables.

and I dont know why

Answer 1

[Star Strider]

It objects to ‘u’ in the variable list.

This works:

eqns=xd
[xh1,xh2,xh3]=solve(eqns,x)