Empty sym: 0-by-1

This is my code where all values to the right of == are known and it keeps giving me the error saying empty sym: 0-by-1. Does anyone have any ideas why this is error keeps happening.

syms f12x f12y f32x f32y f43x f43y f14x f14y t12
    link2x = f12x + f32x == m2*ag2x;
    link2y = f12y + f32y == m2*ag2y;
    link2T = -(r2/2)*sind(theta2)*f12x + (r2/2)*cosd(theta2)*f12y ...
        - (r2/2)*sind(theta2)*f32x + (r2/2)*cosd(theta2)*f32y + t12 == Ig2*aAccel2;
    link3x = -f32x + f43x == m3*ag3x;
    link3y = -f32y + f43y == m3*ag3y;
    link3T = (r3/2)*sind(theta3)*f32x - (r3/2)*cosd(theta3)*f32y - ...
        (r3/2)*sind(theta3)*f43x + (r3/2)*cosd(theta3)*f43y == Ig3*aAccel3;
    link4x = -f43x + f14x == m4*ag4x;
    link4y = -f43y + f14y == m4*ag4y;
    link4T = (r4/2)*sind(theta4)*f43x - (r4/2)*cosd(theta4)*f43y - ...
        (r4/2)*sind(theta4)*f14x + (r4/2)*cosd(theta4)*f14y == Ig4*aAccel4 - T4;
    
    [f12x,f12y,f32x,f32y,f43x,f43y,f14x,f14y,t12] = solve(link2x,link2y,link2T,...
        link3x,link3y,link3T,link4x,link4y,link4T);

Answer 1

[Walter Roberson]

There is no solution to those equations.

m2 = rand() * 10;
m3 = rand() * 10;
m4 = rand() * 10;
ag2x = randn() * 10;
ag3x = randn() * 10;
ag4x = randn() * 10;
ag2y = randn() * 10;
ag3y = randn() * 10;
ag4y = randn() * 10;
Ig2 = rand() * 10;
Ig3 = rand() * 10;
Ig4 = rand() * 10;
aAccel2 = randn() * 10;
aAccel3 = randn() * 10;
aAccel4 = randn() * 10;
T4 = rand() * 10;
r2 = rand() * 10;
r3 = rand() * 10;
r4 = rand() * 10;
theta2 = rand() * 360;
theta3 = rand() * 360;
theta4 = rand() * 360;

syms f12x f12y f32x f32y f43x f43y f14x f14y t12
vars = [f12x f12y f32x f32y f43x f43y f14x f14y t12];

    link2x = f12x + f32x == m2*ag2x;
    link2y = f12y + f32y == m2*ag2y;
    link2T = -(r2/2)*sind(theta2)*f12x + (r2/2)*cosd(theta2)*f12y ...
        - (r2/2)*sind(theta2)*f32x + (r2/2)*cosd(theta2)*f32y + t12 == Ig2*aAccel2;
    link3x = -f32x + f43x == m3*ag3x;
    link3y = -f32y + f43y == m3*ag3y;
    link3T = (r3/2)*sind(theta3)*f32x - (r3/2)*cosd(theta3)*f32y - ...
        (r3/2)*sind(theta3)*f43x + (r3/2)*cosd(theta3)*f43y == Ig3*aAccel3;
    link4x = -f43x + f14x == m4*ag4x;
    link4y = -f43y + f14y == m4*ag4y;
    link4T = (r4/2)*sind(theta4)*f43x - (r4/2)*cosd(theta4)*f43y - ...
        (r4/2)*sind(theta4)*f14x + (r4/2)*cosd(theta4)*f14y == Ig4*aAccel4 - T4;
    
    eqn = [link2x,link2y,link2T,link3x,link3y,link3T,link4x,link4y,link4T] .'

eqn = 

    [A,B] = equationsToMatrix(eqn, vars)

A = 

B = 

    
  rank(A)

ans = 7

  A\B

Warning: Solution does not exist because the system is inconsistent.

ans = 

[Nick Blom]

Thank you for the response, and you are correct all the values to the right of each equation is a known value. So to fix this issue I need to look over my equations.

[Walter Roberson]

link3T and link4T are the problems. Both of those can be expressed in terms of the other equations.

[Nick Blom]

Okay I got it now, thank you