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From: Gerry Jackson <do-not-use@swldwa.uk>
Newsgroups: comp.lang.forth
Subject: Re: exercise in double number arithmetic
Date: Sun, 7 Jul 2024 15:33:37 +0100
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On 07/07/2024 14:17, Krishna Myneni wrote:
> On 7/7/24 00:48, Ahmed wrote:
>> On Sat, 6 Jul 2024 23:50:28 (UTC), Krishna Myneni wrote:
>>
>>> On 7/6/24 16:59, Ahmed wrote:
>> ...
>>> : solution ( -- d)
>>>      1 s>d 43 22 do i 1 m*/ loop d>f
>>>      21 dup s>d rot 2 do I 1 m*/ loop d>f
>>>      f/ fround f>d ;
>>>
>> ...
>>> Krishna
>>
>>
>> You have not to use fround. (42!/21!) is an integer and is multiple of
>> 21!.
>> in other words 42! is multiple of (21!)^2.
>>
> 
> The FROUND is necessary because 42!/21! is too large of an integer to be 
> exactly represented by double-precision fp (IEEE format) and F>D is a 
> truncating operation, not rounding.
> 
> The whole D>F and floating point operations can be dispensed with if we 
> have D/MOD -- a double length version /MOD.
> 
> -- 
> Krishna
> 
> 

There is a +D/MOD in this link

http://www3.cs.stonybrook.edu/~algorith/implement/random-number/distrib/r250.seq

-- 
Gerry