sinusgraph



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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>
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