Help with creating an array from two smaller arrays in a for loop

Hi guys,

I am trying to create a 12x1 array (Fv) from two 1x6 arrays (Mx1 and Mx2). I want the 12x1 array to be populated by the Mx1 values for the first six rows, and the remaing rows to be populated by the Mx2 values. Here is the code I am using:

n = 12;
X1 = linspace(0,L/2,n/2);
X2 = linspace(L/2,L,n/2);

Mx1 = 25.*X1;
Mx2 = 25.*X2 - 50.*(X2-4);

Ft = ones(n,1)
for i = 1:size(Ft,1)
    Fv(i) = Ft(i).*Mx1(i)
    if i >= 6 
       Fv(i) = Ft(i).*Mx2(i)
    end
end

I am getting the follwing errors

Fv =

     0    20    40    60    80     0

Index exceeds the number of array elements. Index must not exceed 6.

Error in beam_deflection_bvp (line 52)
    Fv(i) = Ft(i).*Mx1(i)

Can somebody help please?

Answer 1

[Voss]

L = 8;
n = 12;
X1 = linspace(0,L/2,n/2);
X2 = linspace(L/2,L,n/2);

Mx1 = 25.*X1;
Mx2 = 25.*X2 - 50.*(X2-4);

Fv = [Mx1 Mx2].'

Fv = 12×1

0 20.0000 40.0000 60.0000 80.0000 100.0000 100.0000 80.0000 60.0000 40.0000

[Voss]

I think the way you were attempting would be something like this:

L = 8;
n = 12;
X1 = linspace(0,L/2,n/2);
X2 = linspace(L/2,L,n/2);

Mx1 = 25.*X1;
Mx2 = 25.*X2 - 50.*(X2-4);

Ft = ones(n,1);
Fv = zeros(n,1);
for i = 1:size(Ft,1)
    if i <= 6 
        Fv(i) = Ft(i).*Mx1(i);
    else
        Fv(i) = Ft(i).*Mx2(i-6);
    end
end

Fv

Fv = 12×1

0 20.0000 40.0000 60.0000 80.0000 100.0000 100.0000 80.0000 60.0000 40.0000

[Scott Banks]

Thanks so much, Voss

[Voss]

You're welcome!