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text<->double conversions refactored [message #57476]

Sun, 29 August 2021 13:57

mirek
Messages: 14291
Registered: November 2005

Ultimate Member

After month of development I have today commited refactored text<->double conversion routines (FormatDouble, ScanDouble...)

New routines should(*) guarantee that

- ScanDouble(FormatDouble(x)) == x for all finite doubles
- FormatG(x, 17) returns the same text as printf("%.17g", x) for all doubles

New routines are in the same speed class as ryu, wich seems to be current performance standard (conversion in both directions is around 20ns on modern CPU). (well, I believe my algorithm would be actually faster than ryu if it was doing the same thing, but U++ provides a lot of options which slow it down a bit to basically "ryu equivalent speed").

(*) Well, the theory behind is a bit complicated and I am still ironing details, but from practical point of view I have tested it so far with 300 billions of random double numbers and continue to do so...

https://github.com/ultimatepp/ultimatepp/blob/420697e4630d89 2aaf61b0ab8ba797a810ab7e14/uppsrc/Core/CvFlt.cpp

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Re: text<->double conversions refactored [message #57505 is a reply to message #57476]

Sun, 12 September 2021 20:50

zsolt
Messages: 704
Registered: December 2005
Location: Budapest, Hungary

Contributor

Thanks!

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Re: text<->double conversions refactored [message #57671 is a reply to message #57476]

Tue, 16 November 2021 09:44

Tom1
Messages: 1319
Registered: March 2007

Ultimate Contributor

Hi Mirek,

Was it this change that caused compilation issue with my call:

FormatDoubleFix(value, 3, FD_SIGN|FD_ZEROS);

The compiler tells me the flags are not supported anymore.

How do I do get the same effect as with FD_SIGN|FD_ZEROS?

Best regards,

Tom

[Updated on: Tue, 16 November 2021 10:05]

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Re: text<->double conversions refactored [message #57672 is a reply to message #57671]

Tue, 16 November 2021 10:03

Tom1
Messages: 1319
Registered: March 2007

Ultimate Contributor

Nevermind, I found it. Now it's:

FormatF(value, 3, FD_ZEROS|FD_SIGN);

Best regards,

Tom

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