These are the helpers I described last week to @mohawkjohn. It's basically syntactic sugar for #shape, but I found them to help create more readable scripts.
And the slowdown for calling one method (and possibly caching the number of rows/columns) isn't so great, compared to the complexity of most of the matrix operations we have.
Merge remote-tracking branch 'sciruby/master'
Added helpers #rows and #cols