Subject: code for the transpose of a list of lists.
From: Stavros Macrakis
Date: Tue, 29 Jun 2010 08:11:26 -0400
The big speed gain has been made. Probably more useful to move on to
the next super-bad case than to try to shave 5% more off this one....
Especially since the results are implementation-dependent.
-s
On 2010-06-29, Richard Fateman <fateman at cs.berkeley.edu> wrote:
> Here's another program to time...
>
> (defun $mtrans(r) ;; r must be a maxima matrix
>
> (let* ((j (1- (length r)))
> (k (1- (length (cadr r))))
> (M (make-array (list j k) :initial-contents
> (mapcar #'cdr (cdr r)))))
> (cons '($matrix simp)
> (loop for ind2 fixnum from 0 below k collect
> (cons '(mlist simp)
> (loop for ind1 fixnum from 0 below j collect
> (aref M ind1 ind2)))))))
>
> It appears to be slow on GCL, but may be much faster on some other lisps.
>
> I also don't know about optimization settings for GCL etc.
>
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