MATLAB: Vectors must be the same length.

lengthvectors

Recently started learning MatLab, trying to plot a function graph.
{2a+b=1
2a-b=7
I run this code, I get "Vectors must be the same length."
Error in Untitled2 (line 9)
plot(X,Y1,X,Y2);
Code:
A=[2,1;2,-1]
B=[1;7]
d=det(A)
X=inv(A)*B
A*X
X=-2:0.5:2;
Y1=(-2*A+1)/1;
Y2=(-2*A+7)/(-1);
plot(X,Y1,X,Y2);
grid on

Best Answer

  • You overwrite X:
    A=[2,1;2,-1]
    B=[1;7]
    d=det(A)
    X=inv(A)*B
    A*X
    %X=-2:0.5:2;
    Y1=(-2*A+1)/1;
    Y2=(-2*A+7)/(-1);
    plot(X,Y1,X,Y2);
    grid on
    To avoid this i commented the overwriting line out, because it is not used in the following code.