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Bob Fulks wrote:
> My application was that I had a variable that was a function of
> three other variables:
> Y = function of (S, J, K)
> The relationship I wanted was pretty complex and the variables
> S, J, and K could only have the integer values of 0 through 7. So I
> thought I would just use a look-up table of the values rather than
> try to approximate the relationship with equations.
> To do this I would use a 3 dimensional array which would look like
> a cube with 8 cells on each edge, for a total of 512 cells
> (= 8 * 8 * 8).
I suspect Bob has already thought of this, but for the benefit of
others on the list:
You can simulate a 3-dimensional array using a 1-dimensional array.
You just have to do the array-indexing calculations yourself, but
that's pretty simple.
In Bob's case he would need a 512-element array. Then you would just
multiply S and J by appropriate amounts to offset the array
references into the correct part of the 1-dimensional array.
For an 8 * 8 * 8 array, you could do something like this:
Array: Table[511]; { Table contains elements 0 through 511 }
{ To access element T[S, J, K] of the array, you would say: }
X = Table[S*64 * J*8 + K];
Since S, J, and K range from 0 to 7 in Bob's example, that equation
will produce indices fro 0 to 511. That index calculation is what a
computer language automatically does for you (or at least is SUPPOSED
to do for you :-) when you use a multi-dimensional array.
Gary
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