[Chicken-janitors] #837: statistics: some bugs

[Chicken Trac]

#837: statistics: some bugs
------------------------+---------------------------------------------------
 Reporter:  sjamaan     |       Owner:  petercrlane
     Type:  defect      |      Status:  new        
 Priority:  minor       |   Milestone:             
Component:  extensions  |     Version:  4.7.x      
 Keywords:              |  
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 The scrutinizer found a few bugs in statistics.  The first one in
 {{{wilcoxon-signed-rank-test}}} initially looked like a simple mistake of
 swapping the arguments to {{{list-ref}}}, but even after fixing that I was
 unable to get it to do anything but error out.

 {{{
 #1;> (use statistics srfi-1)
 #2;> (wilcoxon-signed-rank-test (iota 17))
 ;; ERROR
 }}}

 After adding some debugging code, it looks like the indexes are wrong;
 {{{last}}} is determined counting from the end of the list, but it *looks*
 like the code is treating it as if it's counted from the front.  After
 changing that accordingly I still kept getting errors, so I'll leave that
 to you.  I decided to let my patch simply fix these warnings and nothing
 more.

 The second message about {{{wilcoxon-signed-rank-test}}} refers to the
 fact that {{{var-r1}}} is being applied as if it were a procedure.
 However, it's just a number, so this would fail.

 The warning about {{{mcnemars-test}}} is due to the fact that the return
 value of {{{set!}}} is undefined in Scheme (this is different from Common
 Lisp, where {{{setf}}} returns the last value set, I think).  I don't
 really understand the purpose of the named let, so I didn't touch it
 (instead just doing a simple transformation that's always safe), but it
 really looks like it doesn't do anything at all.

 Attached is a patch that gets rid of these warnings.

-- 
Ticket URL: <http://bugs.call-cc.org/ticket/837>
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