MATLAB: Error:An array for multiple LHS assignment cannot contain expressions.

errorlhs

Error: File: Q7.m Line: 12 Column: 2

What does the error mean?

I'm using Matlab to solve Mechanism problems,and here is my code.

I'm pretty sure that it's not InverseRR's problem.I have used that function in other problems ,and it worked.

Hope that somebody who good at it could help me,please><


clc
clear
a1 = 15 ; a2 = 30 ; a3 = 20 ; a4 = 30 ; alpha = 30;
Xq = 50 ; Yq = 8 ; Xr = 70 ; Yr = 8;
dXa = 10 ; dYa = 0;
Xa = 20 ;Ya = a1 ;
I = 1;
BC = sqrt(a3^2 + a4^2 - 2 * a3 * a4 * cos(alpha)) ;
[(theta04),(theta02),dtheta4,dtheta2,ddtheta4,ddtheta2] = InverseRR(Xq,Yq,a3,a2,Xa,Ya,dXa,dYa,ddXa,ddYa,I);
theta2 = theta02 - 180;
theta4 = theta04 - alpha;

Best Answer

Remove the parenthesis

[theta04,theta02,dtheta4,dtheta2,ddtheta4,ddtheta2]  = InverseRR...

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function y=T(theta_Degree)
theta=theta_Degree*pi/180;
y=[cos(theta)^2 sin(theta)^2 2*cos(theta)*sin(theta);sin(theta)^2 cos(theta)^2 -2*cos(theta)*sin(theta);-cos(theta)*sin(theta) cos(theta)*sin(theta) cos(theta)^2-sin(theta)^2];
end

Then type in command line

T(40)

and see the results.

MATLAB: Is it so hard for MATLAB to solve the following symbolic equation

This seems to work

syms rp alpha beta theta psi z
A=cos(alpha)-cos(beta);
B=sin(alpha)-sin(beta);
C=(cos(beta)-1)/tan(beta)-(cos(alpha)-1)/tan(alpha);
R=A*(cos(theta)-cos(psi))+B*cos(theta)*sin(psi);
S=A*sin(theta)*sin(psi)-B*cos(theta)+C*cos(psi);
phi=atan(-R/S);
x=-rp*(cos(theta)*cos(phi)+sin(psi)*sin(theta)*sin(phi))*cos(alpha)-rp*(-cos(theta)*sin(phi)+sin(psi)*sin(theta)*cos(phi))*sin(alpha)+(rp/tan(alpha))*(cos(psi)*sin(phi)*(cos(alpha)-1)+cos(psi)*cos(phi)*sin(alpha));
y=-cos(psi)*sin(phi)*rp;
p=[x;y;z];
T=Rot('y',theta)*Rot('x',psi)*Rot('z',phi);
a1=T*[rp;0;0];
a2=T*[rp*cos(alpha);rp*sin(alpha);0];
a3=T*[rp*cos(beta);rp*sin(beta);0];  
Con1=(p+a1)'*[0;1;0];
Con2=(p+a2)'*[-sin(alpha);cos(alpha);0];
Con3=(p+a3)'*[-sin(beta);cos(beta);0];
disp([Con1; Con2; Con3])
function output=Rot(axis,angle)
syms x y z
if axis==x
    output=[1,0,0;0,cos(angle),-sin(angle);0,sin(angle),cos(angle)];
end
if axis==y
    output=[cos(angle),0,sin(angle);0,1,0;-sin(angle),0,cos(angle)];
end
if axis==z
    output=[cos(angle),-sin(angle),0;sin(angle),cos(angle),0;0,0,1];
end
end

Best Answer

Related Solutions

MATLAB: How to define a function that evaluates in input

MATLAB: Is it so hard for MATLAB to solve the following symbolic equation

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