Storing values of multiple vectors into one 1:100 matrix?

v1=50
v3=75

i2=zeros(1, 100)

for v2=1:100
    b=[v1; v2; v3]
    y=L\b
    x=U\y
end

I am using LU decomposition for the equation Ax=b to solve for the current (x=[i1; i2; i3]) when the voltage (b) is v1=50, v3=75, and every value of v2 from 1 to 100. I already have all the values in the 3x3 matrix for resistance values (A). I need to save all the values of i2 that correspond to the changing v2 values and save them all into a 1x100 matrix.

Answer 1

[Matt J]

for v2=1:100
    b=[v1; v2; v3]
    y=L\b
    x=U\y
    i2(v2)=x(2);
end

[Stephen23]

@Isabella Pollock: with output preallocation, of course!:

v1 = 50;
v3 = 75;
i2 = zeros(1, 100);
for v2 = 1:100
    b = [v1; v2; v3];
    y = L\b;
    x = U\y;
    i2(v2) = x(2);
end

[Shawna Myatt]

I have a question about this bit of code that you posted. I am new to MatLab, so I was able to follow all of it up until the last line. Why did you use i2(v2) = x(2) to get an output of all of the i2 solutions? I can see where the i2 and the v2 come from, but how does the x(2) fit in?

I want to make sure that I am understanding the concepts behind this. Thanks!

[Matt J]

The 3x1 vector x is the solution to A*x=b and x(2) extracts the second element of x.