Re: [Maxima-discuss] [Maxima-commits] [git] Maxima CAS branch master updated. branch-5_40-base-83-ged20729

[Andreas E. <aek...@gm...>]

On Mo 26 Jun 2017 at 20:29, Raymond Toy <toy...@gm...> 
wrote:

> On Sun, Jun 25, 2017 at 2:25 AM, Andreas Eder via Maxima-commits 
> <
> max...@li...> wrote:
>
>> commit e6a7a8af637ee29f549b1dd47633fb08172e17ae
>> Author: Andreas Eder (are_muc) <and...@gm...>
>> Date:   Sun Jun 25 11:06:41 2017 +0200
>>
>>     replaced uses of the half macro with the variable 1//2.
>>     had to adapt relative error bounds for the erf-inverse_erf 
>>     tests
>>     sligthly.
>>
>>
> ​This makes no sense to me.  Why should the results be different?
>
> This needs some investigation.  Is it because the defvar version 
> wasn't
> simplified?​

No, it is simplified.
The defvar is: (defvar 1//2 '((rat simp) 1 2))
That is, as far as I can tell, simplified.
What I suspect is a different order of evaluation. The macro 
version is
expande into a literal at macroexpansion time, whereas the defvar
generates a reference to the variable at compile time. The might 
lead to
different orders of evaluation. But I'm no expert in these 
matters.
The difference is very small and I always expect such things when
dealing with floating point.

'Andreas
-- 
ceterum censeo redmondinem esse delendam