# How to determine if angles match

3 views (last 30 days)
Commented: Madeleine on 21 Feb 2024
I am trying to write code to determine when two precession angles match. Matlab keeps skipping to the last else statement regardless of which elseif statement should be taking precedence.
Unrecognized function or variable 'C21'.
if abs(prec1 - prec2) < 10^-3
prec = prec1;
elseif abs(prec1 - (180 - prec2))< 10^-3
prec = prec1;
elseif abs((360 - prec1) - prec2) < 10^-3
prec = prec2;
else
prec = 360 - prec1;
end
C21, C23, and nutation are arrays that contain ten values calculated earlier in the code.
C12 and C23 are elements of a direction cosine matrix for a two body 1-3-1 rotation sequence and nutation is the angle about body fixed axis u1. precession is the angle about body fixed axis u3.
C12 =
0
0.5207
-0.2255
0.6599
0.0813
0.4857
-0.0558
-0.3070
-0.2298
-0.7950
C23 =
0
0.4887
0.0624
-0.3257
0.0516
-0.7995
0.3638
-0.7010
0.2401
-0.6821
nutation =
0
116.6697
53.6137
79.6703
102.4619
32.9411
127.0446
18.0036
103.4862
69.9394

Walter Roberson on 20 Feb 2024
You would get that behavior if prec1 or prec2 are non-scalar and it does not happen that all of the values pass the tests.
How do i make my variables scalar. I tried using ANY and ALL functions but it I still get a non-scalar error

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