Bill Allombert on Wed, 19 Oct 2011 21:32:18 +0200 |
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Re: Parameters of floating-point arithmetic ? |
On Tue, Oct 18, 2011 at 02:58:11PM -0400, jacques G wrote: > > Question 1: Do the two PARI/GP programs below (flpari, flparam) work > correctly on 64-bit machines ? > > Question 2: Will the fast GP-specific flpari() program work in future versions of PARI/GP ? In both case, it depends what you mean by work, but I think the answer is 1) yes and 2) no. It happens that we are developping a new format for floating point numbers which will allow precision to be set to any number of bits instead of words. > flpari(p=precision(1.)) = { > local(w=#precision(1.,p)); > [2, w, w*=64/#precision(1.,18), 2.>>w]; > } > addhelp(flpari,"flpari(p): parameters of p-decimal PARI/GP floating-point arithmetic"\ > " [base, words, bits, machine epsilon]") I see two problems: 1) The use of # on a real number, which is not well-defined. 2) precision(1.,18) currently return 1. with 19 decimal digits instead of 18. This will change in the future. Cheers, Bill.