Re: Maxima and thread safety

Hello,

this is an other example in which threads work OK

(%i1) load("distribute_over_tranches_thread.lisp");
(%o1)                distribute_over_tranches_thread.lisp
(%i2) 
ee:x[i]^3+3*i^2*x[i]^2+8*i*x[i]^2+6*x[i]^2+6*i^3*x[i]+21*i^2*x[i]+26*i*x[i]
       +11*x[i]+6*i^3+18*i^2+18*i+6$ /* A product of 3 factors */
(%i3) pp:partfrac(1/ee,x[i])$

(%i4) lll:makelist(subst(j,i,pp),j,1,10)$

(%i5) llt:distribute_over_tranches (partfrac(1/ee,x[i]),i,10,3)$

(%i6) is(lll=llt);
(%o6)                                true

In this example one runs partfrac with several main variables. Note that 
partfrac communicates with a program bprog which computes X and Y such as

1/(AB)=X/A+Y/B which in turns makes a lot of euclidean divisions, all of 
them communicating through the special variable *var* which is the 
"main" variable

here x[i] for various values of i. You can note that the various main 
variables don't get mixed by threading, that the x[i] are correctly 
used, so the result

is correct.



Le 09/06/2026 à 17:15, David Scherfgen a écrit :
> You might add this to your examples:
>
> distribute_over_tranches(
>   '(block(
>       [x_n: float(N), x_next, i],
>       for i : 1 thru 1000 do (
>           x_next: 0.5 * (x_n + N / x_n),
>           x_n: x_next
>       ),
>       x_n)),
>   N, 1000, 16);



As for this example, consider the following formulation:

(%i1) compute(N):= (x:float(N), for i : 1 thru 10 do (
           x: 0.5 * (x + N / x)), x)$

(%i2) ll:distribute_over_tranches(compute(i),i,100,5)$

(%i3) for i from 1 thru 100 do if (ll[i]-float(sqrt(i))>1e-15) then 
print(i);
73
89
95

(%o3)                                done

The error in question in these 3 cases is of order of 2e-15.  In other 
words this also seems to work.

Note that if you iterate the inner loop to 1000 it takes forever to run, 
maybe this what can be taken as thread problem.

-- 
Michel Talon

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