Why does the code output something that's clearly false?
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It's supposed to check if A is orthogonal. Here's the code:
A= [2/3 2/3 1/3; -2/3 1/3 2/3; 1/3 -2/3 2/3];
Id= [1 0 0; 0 1 0; 0 0 1];
disp("A is orthogonal");
disp("A is orthogonal B");
disp('A is not orthogonal');
I checked myself and both of the first two tests should output True. But they don't. I wasn't even supposed to use both of the first two at once since they both are true but the even when I use only one, it still says that A is not orthogonal when it is?
Why is this happening?
Christoph F. on 24 Nov 2017
> Why is this happening?
Look at the value of
MatLAB uses numeric methods to invert matrices with inv(), and numeric methods are subject to numeric errors. This starts with finite machine precision (MatLAB has no way to represent a value like 2/3 accurately with a double precision floating point number).