what is the problem with the code?

clc;
close all; 
clear all;

% The variabel
L0 = 0.5;
k = 10;

AO = 0.3;
Hyp = 0.8 ;
BD = Hyp * sind(20) + 0.3;
DP = BD/2;

OD = 0.8 * cosd(20);
DBdiff = (BD/2) - (AO/2);
Sl = sqrt((OD^2) + (DBdiff^2));
DeltX = Sl - L0;
F = k * DeltX;

alpha = atand(DBdiff/OD)

alpha = 10.3141

%OA Part 
Sx = F * cosd(alpha)

Sx = 2.5983

Sy = F * sind(alpha)

Sy = 0.4729

%SUMFx=0 -> Ax + Ox + Sx = 0
%SUMfy=0 -> Oy - Ay + Sy = 0
%SUMM0=0 -> T + (0.15)(Sx)-(0.3)(Ax) = 0

%BD Part
Px = -F * acosd(alpha)

Px = -0.0000e+00 - 4.5763e+02i

Py = -F * asind(alpha)

Py = -2.3769e+02 + 4.5763e+02i

%SUMFx=0 -> Dx + Bx - Px = 0 
%SUMFy=0 -> Dy - By - Py = 0 
%SUMM0=0 -> (DP)(Px) + (Bx)(BD) = 0

%AB Part
F1 = 0.3 * 10 * 1/2

F1 = 1.5000

F2 = 0.3 * 5

F2 = 1.5000

F1x = F1 * cosd(70)

F1x = 0.5130

F2x = F2 * cosd(70)

F2x = 0.5130

F1y = F1 * sind(70)

F1y = 1.4095

F2y = F2 * sind(70)

F2y = 1.4095

%SUMFx=0 -> Ax + Bx + F1x + F2x = 0
%SUMFy=0 -> -Ay - By - F1y - F2y = 0
%SUMMa=0 -> -F1y(Hyp-(2/3)*0.3*cosd(20)) - F2y(Hyp-(1/2)*0.3*cosd(20)) -
%By(Hyp) + Bx(BD-AO) - F1x(0.6 * sind(20)) - F2x(0.65 * sind(20)) = 0

M = [1 0 0 0 1 0 0 0 0
    0 -1 0 0 0 1 0 0 0
    -(0.3) 0 0 0 0 0 0 0 1
    0 0 1 0 0 0 1 0 0
    0 0 0 -1 0 0 0 1 0
    0 0 (BD) 0 0 0 0 0 0
    1 0 1 0 0 0 0 0 0
    0 -1 0 -1 0 0 0 0 0
    0 0 (BD-AO) -(Hyp) 0 0 0 0 0]

M = 9×9

1.0000 0 0 0 1.0000 0 0 0 0 0 -1.0000 0 0 0 1.0000 0 0 0 -0.3000 0 0 0 0 0 0 0 1.0000 0 0 1.0000 0 0 0 1.0000 0 0 0 0 0 -1.0000 0 0 0 1.0000 0 0 0 0.5736 0 0 0 0 0 0 1.0000 0 1.0000 0 0 0 0 0 0 0 -1.0000 0 -1.0000 0 0 0 0 0 0 0 0.2736 -0.8000 0 0 0 0 0

N= [-Sx;
    -Sy;   
    -(F1)*(Sx);   
    Px; 
    Py;   
    -(DP)*(Px); 
    -(F1x) -(F2x);
    (F1y) + (F2y); 
    (F1y)*(Hyp-(2/3)*0.3*cosd(20))+(F2y)*(Hyp-(1/2)*0.3*cosd(20))+(F1x)*(0.6*sind(20)) + (F2x)*(0.65*sind(20));]

Error using vertcat
Dimensions of arrays being concatenated are not consistent.

X = M\N

[Vladik Berg]

i get "Dimensions of arrays being concatenated are not consistent." on N = [-Sx

[Torsten]

N= [-Sx;...

-Sy;...

-(F1)*(Sx);...

Px;...

Py;...

-(DP)*(Px);...

-(F1x)-(F2x);...

(F1y)+(F2y);...

(F1y)*(Hyp-(2/3)*0.3*cosd(20))+(F2y)*(Hyp-(1/2)*0.3*cosd(20))+(F1x)*(0.6*sind(20))+(F2x)*(0.65*sind(20))];

Answer 1

[Walter Roberson]

      -(F1x) -(F2x);

That is not subtraction giving back a scalar. That is two independent elements. Just like in M you have

0 -1

and you expect it to be a vector of length two, when you have something of the form

A -B

inside [] or {} then you get a pair of elements.

    -(F1x) - (F2x);

on the other hand would be subtraction.

Answer 2

[Cris LaPierre]

There is ambiguity in one of your rows and, since the code is building an array, MATLAB is not doing what you intended. Specifically, a '-' can indicate subtraction as well as a negative number. Since you are building an array, how you use your spaces matters.

The problem is in this line:

-(F1x) -(F2x);

Because of the spacing inside square brackets, this is being treated as two negative numbers rather than a subtraction. Either of the following fixes that.

-(F1x)-(F2x);
% or
-(F1x) - (F2x);