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Hi Sean, I would like to suggest an improvement to your code. I think that it would be far more simple if to get the orientation of the member you use the function math.atan2 (it provides an angle between -pi/2 and pi/2 but that’s enough).

Here the code that I implemented (I tested it and everything works fine as with yours).

```
def memberOrientation(memberNO):
memberIndex = memberNO - 1 #Index identifying member in arrays of members
node_i = members[memberIndex][0]
node_j = members[memberIndex][1]
xi = nodes[node_i - 1][0] #x-coord of node i
yi = nodes[node_i - 1][1] #y-coord of node i
xj = nodes[node_j - 1][0] #x-coord of node j
yj = nodes[node_j - 1][1] #y-coord of node j
dx = xj-xi #x component of member vector
dy = yj-yi #y component of member vector
#Angle of member
theta = math.atan2(dy,dx)
#Length of member
L = math.sqrt(dx**2+dy**2)
return [theta, L]
```

Thanks @Oliviero - yes this is a great improvement. I wasn’t familiar with that function at the time of writing…a great time saver

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