RPL mini-challenge: Create an anti-Identity Matrix

[Claudio L.]

(05-15-2018 03:31 PM)David Hayden Wrote:  

Code:

DUPDUP 2. \->LIST 1. CON SWAP IDN -

With input 30, it takes 2.47 seconds on a 50g.

A modified version of Claudio's program takes 3.4 seconds:

Code:

IDN DUP 1. CON SWAP -

I like your improvement on my short version. I was doing NEG on the identity matrix, way slower than using SWAP and subtracting, that has to save significant time.

Now I can't fully understand why the code above, being the EXACT same commands except you added 2 ->LIST and replaced one DUP with one DUPDUP, would be 30% faster. Isn't it doing the same thing? Or are CON and IDN much faster when you use size arguments in lists?
I just can't explain it.