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Re: Value with type float [message #58231 is a reply to message #58227]

Fri, 01 April 2022 11:03

mirek is currently offline

mirek
Messages: 14256
Registered: November 2005

Ultimate Member

abductee23 wrote on Thu, 31 March 2022 11:51

having a flot in memory - writing it out through value/json , then reading it again incurs a conversion and its not the same number - ( i guess on a personal level i am probably puzzled how this is not bothering you - but thats beside the point)

But that is altogether different issue! Converting float or double to decimal text and back involves completely different set of problems.

Frankly, current "stable" version (2021.1) has this botched up a bit. Here the IEEE standard states that 15 digit double numbers must be converted from text and back without a change. We were short on this promise, but this is hopefully fixed in the upcoming version.

Anyway, conversion from float to double is basically only adding zeroes to mantissa, converting from double back to float involves in most cases (*) just rounding the same additional bits (if they are zero, rounding is obviously down).

(*) - there is of course issue of range (float is about e-38 to e+38 while double e-308 to e-308) and denormals, but that is in most cases bedides the point..

Mirek

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[Message index]

		Value with type float By: abductee23 on Thu, 03 March 2022 13:34
		Re: Value with type float By: mirek on Sat, 19 March 2022 10:38
		Re: Value with type float By: abductee23 on Thu, 31 March 2022 11:51
		Re: Value with type float By: Tom1 on Thu, 31 March 2022 13:49
		Re: Value with type float By: Tom1 on Thu, 31 March 2022 15:14
		Re: Value with type float By: mirek on Fri, 01 April 2022 11:07
		Re: Value with type float By: Tom1 on Fri, 01 April 2022 11:13
		Re: Value with type float By: Tom1 on Fri, 01 April 2022 12:06
		Re: Value with type float By: Tom1 on Fri, 01 April 2022 14:03
		Re: Value with type float By: Tom1 on Fri, 01 April 2022 15:26
		Re: Value with type float By: mirek on Sat, 02 April 2022 01:31
		Re: Value with type float By: mirek on Sat, 02 April 2022 01:31
		Re: Value with type float By: mirek on Sat, 02 April 2022 09:43
		Re: Value with type float By: Tom1 on Sat, 02 April 2022 10:55
		Re: Value with type float By: mirek on Sat, 02 April 2022 11:26
		Re: Value with type float By: Tom1 on Sat, 02 April 2022 13:31
		Re: Value with type float By: mirek on Mon, 11 April 2022 16:52
		Re: Value with type float By: Tom1 on Tue, 12 April 2022 09:26
		Re: Value with type float By: mirek on Tue, 12 April 2022 13:40
		Re: Value with type float By: Tom1 on Tue, 12 April 2022 13:54
		Re: Value with type float By: Tom1 on Tue, 10 May 2022 13:21
		Re: Value with type float By: mirek on Tue, 10 May 2022 15:44
		Re: Value with type float By: Tom1 on Tue, 10 May 2022 20:08
		Re: Value with type float By: mirek on Tue, 10 May 2022 21:26
		Re: Value with type float By: Tom1 on Wed, 11 May 2022 08:20
		Re: Value with type float By: mirek on Fri, 03 June 2022 10:52
		Re: Value with type float By: Tom1 on Fri, 03 June 2022 12:03
		Re: Value with type float By: mirek on Wed, 04 October 2023 09:55
		Re: Value with type float By: Tom1 on Wed, 04 October 2023 12:08
		Re: Value with type float By: mirek on Fri, 06 October 2023 12:51
		Re: Value with type float By: Tom1 on Fri, 06 October 2023 13:40
		Re: Value with type float By: mirek on Fri, 06 October 2023 13:54
		Re: Value with type float By: Tom1 on Fri, 06 October 2023 14:28
		Re: Value with type float By: mirek on Mon, 30 October 2023 10:34
		Re: Value with type float By: Tom1 on Mon, 30 October 2023 12:27
		Re: Value with type float By: mirek on Mon, 30 October 2023 13:37
		Re: Value with type float By: mirek on Fri, 01 April 2022 11:03
		Re: Value with type float By: jimlef on Tue, 06 September 2022 01:41
		Re: Value with type float By: Oblivion on Tue, 06 September 2022 22:42
		Re: Value with type float By: jimlef on Thu, 08 September 2022 14:49

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