Re: [Maxima-discuss] Fatal error

[Michel T. <ta...@lp...>]

Le 05/06/2018 à 06:32, Robert Dodier a écrit :
> On 2018-06-04, Stavros Macrakis<mac...@al...>  wrote:
>
>> Maxima 5.41.0a_dirtyhttp://maxima.sourceforge.net
>> using Lisp SBCL 1.3.18
>> (%i1) load(drawdf);
>> (%o1)
>> E:/maxima-5.41.0a/bin/../share/maxima/5.41.0a_dirty/share/diffequations/\
>> drawdf.mac
>> (%i2) drawdf([y,-9*sin(x)-y/5], [x,-10,10], [y,-10,10], tstep=0.05,
>>                soln_arrows=true, point_size=0.5,
>>                points_at([0,0], [2*%pi,0], [-2*%pi,0]),
>>                field_degree='solns,
>>                saddles_at([%pi,0], [-%pi,0]));
>>
>> ÿ%
>> fatal error encountered in SBCL pid 2684(tid 0000000001356500):
>> %PRIMITIVE HALT called; the party is over.
> Some investigation shows the trouble is caused by calls to 'translate'.
> In the example as shown above, there are 1336 calls to translate (as
> determined by 'timer' and 'timer_info'). drawdf constructs a large
> number of short functions (maybe one for each point in the plot? I
> didn't look carefully) and calls the Maxima->Lisp translator, presumably
> in hope of greater speed of evaluation.
>
>
>


Indeed tracing translate shows that the above calls repeatedly translate 
on f_rk_4.   One gets things such as:
1 Enter translate [translate(f_rk_4)]
1 Exit  translate [f_rk_4]
1 Enter translate [translate(f_rk_4)]
1 Exit  translate [f_rk_4]
1 Enter translate [translate(f_rk_4)]
1 Exit  translate [f_rk_4]
1 Enter translate [translate(f_rk_4)]
1 Exit  translate [f_rk_4]
1 Enter translate [translate(f_rk_4)]
1 Exit  translate [f_rk_4]
1 Enter translate [translate(f_rk_4)]
...
Which seems to point to an error in the invocation of translate.

Anyways removing the call to translate doesn't make a very significant 
difference:

without translate
(%i5) drawdf([x*(1-x-y), y*(3/4-y-x/2)], [x,0,1.1], [y,0,1], 
duration=40, soln_arrows=true, field_degree=2, point_at(1/2,1/2), 
solns_at([0.1,0.2], [0.2,0.1], [1,0.8], [0.8,1], [0.1,0.1], [0.6,0.05], 
[0.05,0.4], [1,0.01], [0.01,0.75])) $
Evaluation took 8.5190 seconds (8.5310 elapsed) using 1329.628 MB.

with translate
(%i8) drawdf([x*(1-x-y), y*(3/4-y-x/2)], [x,0,1.1], [y,0,1], 
duration=40, soln_arrows=true, field_degree=2, point_at(1/2,1/2), 
solns_at([0.1,0.2], [0.2,0.1], [1,0.8], [0.8,1], [0.1,0.1], [0.6,0.05], 
[0.05,0.4], [1,0.01], [0.01,0.75])) $
Evaluation took 6.9180 seconds (6.9290 elapsed) using 1252.857 MB.

and more importantly the above example now runs to completion in around 
10s.  So i think it is advisable to remove the call to translate
in make_f_rk_4 that is  so that the last line is:
         [dxdt_var,dydt_var]))))$


-- 
Michel Talon