Sorry, no need to concat any more. Replace second line by
xt : setify(makelist([string(i/4*pi),ev(i/4*%pi,numer)],i,-6,6))$
reyssat a ?crit :
> This is simpler : use the option xtics directly in draw2d :
>
> load(draw)$
> xt : setify(makelist([concat(string(i/4*pi)),ev(i/4*%pi,numer)],i,-6,6))$
> draw2d(xtics = xt,
> explicit(sin(x),x,-5,5) )$
>
>
>
>
> reyssat a ?crit :
>> J. Simons a ?crit :
>>
>>> L.S.,
>>>
>>> How can Maxima produce a sinusgraph with a graduation-scale
>>> consisting of rational multiples of %pi (see attachment).
>>>
>> I don't see any attachment, but you may try using draw2d with
>> user_preamble. For instance :
>>
>> (%i1) load(draw)$
>> (%i2) p:"set xtics (\"-pi\" -3.14, \"0\" 0, \"pi\" 3.14)";
>> (%o2) set xtics ("-pi" -3.14, "0" 0, "pi" 3.14)
>> (%i3) draw2d(explicit(sin(x)-1,x,-5,5),
>> user_preamble=p);
>>
>> of course you may want to "compute" the preamble. This is an attempt
>> (probably not very clean) :
>> (%i4) p:concat("set xtics(")$
>> for i:-5 thru 5 do (v:string(i/4*pi), p:concat(p,\",v,\","
>> ",string(ev(i/4*%pi,numer))), if i<5 then p:concat(p,","))$
>> p:concat(p,")")$
>> (%i6)
>> (%i7) draw2d(explicit(sin(x)-1,x,-5,5),
>> user_preamble=p);
>>
>> Eric Reyssat
>>
>>
>>>
>>> Thanking you in advance for your answer.
>>>
>>> Regards,
>>>
>>> Jos? Simons
>>> ------------------------------------------------------------------------
>>>
>>>
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>>> Maxima at math.utexas.edu
>>> http://www.math.utexas.edu/mailman/listinfo/maxima
>>>
>>
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>>
>>
>
>