Bill Allombert on Thu, 09 Jun 2005 16:18:37 +0200 |
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Re: dumb question about rationals |
On Thu, Jun 09, 2005 at 02:20:33PM +0200, Vincent Torri wrote: > > Hello, > > my program is almost working. But in some cases, i got the error message: > > impossible assignment I-->S This mean you try to convert (with itos) a PARI object to a C long integer and either the object is not a PARI integer, or it is too large to fit in a signed long. > It occurs when i try to get the value of the denominator of a rational. > The rational type is 4 and the denominator type is 1. Please use symbolic name for type (4=t_FRAC, 1=t_INT, etc.) > When could this error appear ? Probably somewhere where you use itos(). > Another question: What i do is the following : > > 1) I allocate 2 arrays of GEN (with malloc), say t1, t2 > 2) I init the 2 arrays > 3) I do my stuff (a loop) : > a) i fill t2 with modified values of t1 > b) t1 = t2 (i do a loop on k : t1[k] = t2[k]) > 4) store the values of t1, at the end of the loop > 5) I free the 2 arrays. > > Could the problem above (it appears in step 4) arise from the fact that I > use allocated arrays and I'm doing step 3)b) ? Should I use PARI vector > instead of arrays Usually it is simpler to use PARI vector allocated in the stack than using malloc, though there are exceptions. If you do GEN *T=(GEN*)malloc(1000,sizeof(GEN)) for(i=0;i<1000;i++) T[i]=stoi(i) then T is actually an array of pointer to objects stored in the PARI stack. If you gerepile() the stack, T will not be updated and element of T will point to random data. Cheers, Bill.