[Jprogramming] Monday Morning Wake Up Exercise

[Dan Bron]

Linda wrote:
> (Y viewmat i.4)-:Y4 viewmat i.4
> (Y4 viewmat i.5)-:Y5 viewmat i.5

> Or maybe this should be:
> (Y viewmat i.5)-:Y5 viewmat i.5

I’m not sure what you’re trying to test with those -:s, but note that in the standard J IDEs, the result of viewmat (of any input) is always the same; specifically, it’s always i.0 0  (a 0x0 square of integers). 

So, for example,

   (viewmat ?~ 13) -: viewmat #:i.67
1

Note that both the arrays ?~13 and #:i.67 and their respective viewmat visualizations are completely different animals. 

The -: is telling you nothing (except that viewmat is defined to always return i.0 0).

-Dan