Orthogonal array calculation
 

I am having a bit of a trouble understanding orthogonal array calculation. I am trying to understand the following example given by the lecturer: (not exact words, just what I managed to jot down)

a function that takes 20 inputs of true and false values will have a:

single mode calculation of: 2x20
double mode calculation: (20x(20-1)x2)x4

I think I managed to understand the single mode because there are 2 values and 20 parameters.

I also think I understand some of the double mode. 20x because there are 20 input parameters and the x2 because there are 2 values.

The part i don't understand about the double is 20-1 and x4.

Re: Orthogonal array calculation
 

You'll have to ask your lecturer. Your notes are not complete enough to even allow an understanding of your question, let alone give an answer.

Re: Orthogonal array calculation
 

The only thing that I know about orthogonality is that two vectors are orthogonal if, when multiplied, they equal 0. Lol. Hope that helps. But I doubt it does.

Re: Orthogonal array calculation
 

its not only vectors, anything can be orthgonal
orthogonal only means that the objects are at right angles to each other

I searched google came across these websites which may be of help

http://mathworld.wolfram.com/OrthogonalArray.html

http://www.research.att.com/~njas/doc/OA.html