David,

I think I see the fact families in Linda's (and Roger's) uni-color stripes,
but only in the addition table, not the subtractions. That connection is
harder for me to see.

Reusing your definitions a little I get the following which produces the
families 3 to 10. I especially want to explore how A. was used so
effectively.

   addends =: [: i. [: <. 1 1r2&p.

   fact_family =: [: (3 A. (, -/))"1 }.@:(,. addends)

   fact_family each 3+i. 8

+-----+-----+-----+-----+-----+-----+-----+------+

|1 2 3|1 3 4|1 4 5|1 5 6|1 6 7|1 7 8|1 8 9|1 9 10|

|     |2 2 4|2 3 5|2 4 6|2 5 7|2 6 8|2 7 9|2 8 10|

|     |     |     |3 3 6|3 4 7|3 5 8|3 6 9|3 7 10|

|     |     |     |     |     |4 4 8|4 5 9|4 6 10|

|     |     |     |     |     |     |     |5 5 10|

+-----+-----+-----+-----+-----+-----+-----+------+

Thanks,


On Wed, Jan 14, 2015 at 4:58 PM, David Lambert <[email protected]>
wrote:

> The uni-color stripes in Linda's viewmat operator tables display fact
> families.  Shame to lose that.
>
> Are zeros permitted?
>
>
>    ( addends =: [: i. [: <. 1 1r2&p. )&.>i.11
> +-+-+---+---+-----+-----+-------+-------+---------+---------+-----------+
> |0|0|0 1|0 1|0 1 2|0 1 2|0 1 2 3|0 1 2 3|0 1 2 3 4|0 1 2 3 4|0 1 2 3 4 5|
> +-+-+---+---+-----+-----+-------+-------+---------+---------+-----------+
>
>       ( fact_family =: [: (3 A. (, -/))"1 (,. addends) )&.>i.11
> +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-------+
> |0 0 0|0 1 1|0 2 2|0 3 3|0 4 4|0 5 5|0 6 6|0 7 7|0 8 8|0 9 9|0 10 10|
> |     |     |1 1 2|1 2 3|1 3 4|1 4 5|1 5 6|1 6 7|1 7 8|1 8 9|1  9 10|
> |     |     |     |     |2 2 4|2 3 5|2 4 6|2 5 7|2 6 8|2 7 9|2  8 10|
> |     |     |     |     |     |     |3 3 6|3 4 7|3 5 8|3 6 9|3  7 10|
> |     |     |     |     |     |     |     |     |4 4 8|4 5 9|4  6 10|
> |     |     |     |     |     |     |     |     |     |     |5  5 10|
> +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-------+
>
>
​​

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