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Re: Range Reduction Using Big Number Arithmetic

From Krishna Myneni <krishna.myneni@ccreweb.org>
Newsgroups comp.lang.forth
Subject Re: Range Reduction Using Big Number Arithmetic
Date 2026-09-04 07:45 -0500
Organization A noiseless patient Spider
Message-ID <117eei7$kpil$1@dont-email.me> (permalink)
References <115pm90$3cl9h$1@dont-email.me> <1168f21$bnk$1@dont-email.me> <116sa3b$2dpj8$4@dont-email.me> <117cuca$4f48$1@dont-email.me> <117dl09$u1dl$1@dont-email.me>

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On 9/4/26 00:29, marcel hendrix wrote:
> On 9/4/2026 1:03 AM, Krishna Myneni wrote:
> [..]
>> I am porting the range reduction code in branred.c to Forth.
> Please note that setting the FPU rounding mode may affect calls to/by 
> foreign code (e.g. callbacks).
> 
> -marcel

That would be a problem for signal handlers and interrupt service 
routines, but only if they deal with floating point arithmetic. That's 
probably pretty rare.

In general, if double-precision and round-to-nearest are not your 
default mode, words which change the fpu control word should save the 
prior control word and restore it before they exit.

JVN's double-double arithmetic Forth code assumes the fpu control 
settings and does not set or restore the fpu control word.

It is also important that the Forth interpreter's conversion of decimal 
input to double precision floating point must be accurate to within 1 
ulp for double-double arithmetic to work. These issues we have been 
talking about, decimal string to floating point binary and vice versa 
and range reduction, are connected to the accuracy of floating point 
calculations.

--
Krishna

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Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-15 07:32 -0500
  Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-15 07:48 -0500
  Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-20 22:01 -0500
    Re: Range Reduction Using Big Number Arithmetic albert@spenarnc.xs4all.nl - 2026-08-22 19:31 +0200
      Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-31 08:49 -0500
    Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-28 10:39 -0500
      Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-28 10:42 -0500
      Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-03 18:03 -0500
        Re: Range Reduction Using Big Number Arithmetic marcel hendrix <mhx@iae.nl> - 2026-09-04 07:29 +0200
          Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-04 07:45 -0500
            Re: Range Reduction Using Big Number Arithmetic marcel hendrix <mhx@iae.nl> - 2026-09-04 15:29 +0200
              Re: Range Reduction Using Big Number Arithmetic albert@spenarnc.xs4all.nl - 2026-09-05 12:27 +0200
                Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-05 08:39 -0500
        Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-09 07:37 -0500
          Re: Range Reduction Using Big Number Arithmetic peter <peter.noreply@tin.it> - 2026-09-09 18:49 +0200
            Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-09 15:06 -0500
            Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-10 19:03 -0500
              Re: Range Reduction Using Big Number Arithmetic peter <peter.noreply@tin.it> - 2026-09-11 14:56 +0200
                Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-11 09:17 -0500
                Re: Range Reduction Using Big Number Arithmetic peter <peter.noreply@tin.it> - 2026-09-11 17:04 +0200
                Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-11 10:46 -0500
                Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-11 13:24 -0500
                Re: Range Reduction Using Big Number Arithmetic peter <peter.noreply@tin.it> - 2026-09-11 23:21 +0200
                Re: Range Reduction Using Big Number Arithmetic peter <peter.noreply@tin.it> - 2026-09-12 00:42 +0200
                Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-11 18:33 -0500
                Re: Range Reduction Using Big Number Arithmetic peter <peter.noreply@tin.it> - 2026-09-12 11:04 +0200
                Re: Range Reduction Using Big Number Arithmetic Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-09-12 10:33 -0500

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