# Truss analysis with Matlab

1. Jul 16, 2014

### Maylis

Hello, I have been working on this Truss problem and have not managed to get it right. I have checked my equations over and over and everything seems to check out, but I only get 4/24 on the autograder.

Here is my paper worked out.

Here is my Code. Because I don't like the opposite sign convention from the problem statement, I just used the normal sign convention and multiplied by -1, -(A\b). Whether I keep it -(A\b) or A\b, I still get 4/24 points.
Code (Text):
function T = trussAnalyze(Px,Pz)
A = [cosd(180),cosd(30),0,cosd(270),cosd(atand(3/4)+180),0;
0, cosd(210),cosd(240),0,0,0;
0,0,cosd(60),cosd(90),0,cosd(180);
sind(180),sind(30),0,sind(atand(3/4)+180),sind(270),0;
0,sind(210),sind(240),0,0,0;
0,0,sind(60),sind(90),0,sind(180)];
b =[0;Px;0;0;Pz;0];
T = -(A\b);
I run the autograder and here is an example of the feedback I get
Code (Text):
In test case 2:

*Right size and class, but wrong values (even accounting for roundoff)
Argument 1:
0

Argument 2:
100
EDIT: Wrote it on a paper and uploaded as PDF so that my work is easier to see.

#### Attached Files:

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• ###### TrussAnalyze attempt 1.pdf
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Last edited: Jul 16, 2014
2. Jul 17, 2014

### Maylis

my -0.6 and 1 were switched