a curiosity: FLOAT returns double for single float

> Look for the FLOAT macro in clmacs.lisp.

Oh -- yup, that'll do it.

Thanks for the info.

best

Robert Dodier

On 6/20/12, Raymond Toy <toy.raymond at gmail.com> wrote:
> On Wed, Jun 20, 2012 at 8:37 AM, Robert Dodier
> <robert.dodier at gmail.com>wrote:
>
>> Hi, why does this happen?
>>
>> $ sh maxima-local -l clisp
>> Maxima branch_5_27_base_135_gdf1376c_dirty http://maxima.sourceforge.net
>> using Lisp CLISP 2.49 (2010-07-07)
>> Distributed under the GNU Public License. See the file COPYING.
>> Dedicated to the memory of William Schelter.
>> The function bug_report() provides bug reporting information.
>> (%i1) :lisp (defparameter foo 1f0)
>> FOO
>> (%i1) :lisp (defparameter bar (float foo))
>> BAR
>> (%i1) :lisp (type-of foo)
>> SINGLE-FLOAT
>> (%i1) :lisp (type-of bar)
>> DOUBLE-FLOAT
>> (%i1) :lisp (eq foo bar)
>> NIL
>>
>>
>> I've tried this with Clisp, SBCL, and ABCL. They all give the same
>> results. Incidentally without Maxima (just Lisp) the return value of
>> (FLOAT 1f0) is single float.
>>
>> CLHS for FLOAT says that it returns its argument if the argument is a
>> float and there is no prototype given. So I'm surprised to see that a
>> double is returned for a single float argument.
>>
>> There is *READ-DEFAULT-FLOAT-FORMAT* which is DOUBLE-FLOAT in Maxima,
>> but I wouldn't expect that to affect the function FLOAT.
>>
>>
> Look for the FLOAT macro in clmacs.lisp.
>
> I think I did this long ago because there are many uses of FLOAT in maxima,
> but all uses of FLOAT implicitly assumed gcl's version of FLOAT.  In gcl, a
> double-float and single-float are the same and are 64-bit floats.  Gcl's
> short-float is a single-float.
>
> Ray
>