Matrix dimensions must agree

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Meaghan
Meaghan il 17 Ott 2017
Risposto: Gautam il 23 Ott 2024
Hi, I am having trouble with solving a system of linear equations. I am getting an error that the matrix dimensions must agree and i cannot divide a/b.
if true
x1=167.48;
x2 = 355.63;
x3 = 355.63;
x4=264.58;
x5=62.93;
x6=167.48;
a= 1000.*(6+.005.*x1)./1.1 ;
b= 1000.*(6+.005.*x2)./1.1 ;
c= 1000.*(6+.005.*x3)./1.1 ;
d= 1000.*(6+.005.*x4)./1.1 ;
e= 1000.*(6+.005.*x5)./1.1;
f= 1000.*(6+.005.*x6)./1.1;
g= (1000.*(6+.005.*x1)/1.1).^-1;
h= (1000.*(6+.005.*x2)/1.1).^-1;
i= (1000.*(6+.005.*x3)/1.1).^-1;
j=(1000.*(6+.005.*x4)/1.1).^-1 ;
k=(1000.*(6+.005.*x5)/1.1).^-1;
l=(1000.*(6+.005.*x6)/1.1).^-1 ;
r = -.0024
a = [1,0,0,0,0,0, 0,0,0,0,0,0, g,0,0,0,0,0 0,0,0,0,0,0;
0,1,0,0,0,0, 0,0,0,0,0,0, 0,h,0,0,0,0 0,0,0,0,0,0;
0,0,1,0,0,0, 0,0,0,0,0,0, 0,0,i,0,0,0 0,0,0,0,0,0;
0,0,0,1,0,0, 0,0,0,0,0,0, 0,0,0,j,0,0 0,0,0,0,0,0;
0,0,0,0,1,0, 0,0,0,0,0,0, 0,0,0,0,k,0 0,0,0,0,0,0;
0,0,0,0,0,1, 0,0,0,0,0,0, 0,0,0,0,0,l 0,0,0,0,0,0;
r,0,0,0,0,0 1,0,0,0,0,0 0,0,0,0,0,0 0,0,0,0,0,0;
0,r,0,0,0,0 0,1,0,0,0,0 0,0,0,0,0,0 0,0,0,0,0,0;
0,0,r,0,0,0 0,0,1,0,0,0 0,0,0,0,0,0 0,0,0,0,0,0;
0,0,0,r,0,0 0,0,0,1,0,0 0,0,0,0,0,0 0,0,0,0,0,0;
0,0,0,0,r,0 0,0,0,0,1,0 0,0,0,0,0,0 0,0,0,0,0,0;
0,0,0,0,0,r 0,0,0,0,0,1 0,0,0,0,0,0 0,0,0,0,0,0;
0,0,0,0,0,0 a,0,0,0,0,0 0,0,0,0,0,0 1,0,0,0,0,0;
0,0,0,0,0,0 0,b,0,0,0,0 0,0,0,0,0,0 0,1,0,0,0,0;
0,0,0,0,0,0 0,0,c,0,0,0 0,0,0,0,0,0 0,0,1,0,0,0;
0,0,0,0,0,0 0,0,0,d,0,0 0,0,0,0,0,0 0,0,0,1,0,0;
0,0,0,0,0,0 0,0,0,0,e,0 0,0,0,0,0,0 0,0,0,0,1,0;
0,0,0,0,0,0 0,0,0,0,0,f 0,0,0,0,0,0 0,0,0,0,0,1;
0,0,0,0,0,0 0,0,0,0,0,0 0,0,0,0,0,0 1,0,0,0,0,-1;
0,0,0,0,0,0 0,0,0,0,0,0 0,0,0,0,0,0 0,1,0,0,0,-1;
0,0,0,0,0,0 0,0,0,0,0,0 0,0,0,0,0,0 0,0,1,0,0,-1;
0,0,0,0,0,0 0,0,0,0,0,0 0,0,0,0,0,0 0,0,0,1,0,-1;
0,0,0,0,0,0 0,0,0,0,0,0 0,0,0,0,0,0 0,0,0,0,1,-1;
0,0,0,0,0,0 0,0,0,0,0,0 1,1,1,1,1,1 0,0,0,0,0,0;];
% 1 2 3 4 5 6 7 8 9 101112131415161718192021222324
b = [0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;];
x= size(a)
z = size(b)
y = a/b
end

Accedi per rispondere a questa domanda.

Risposte (2)

KSSV
KSSV il 17 Ott 2017
Replace:
y = a/b
with
y = a\b
Gautam
Gautam il 23 Ott 2024
Hello Meaghan,
The reason you get this error is because you cannot divide two matrices the way you divide two scalars.
To find the solution to a system of linear equations, use the “\” operation instead of “/”. Like, “y = a\b”
Hope this helps

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