Posted by jpluimers on 2016/12/08
SQL server % (modulo, not mod) operator doesn’t like floats (with reason).
You should get rid of the floats as they will give inaccurate results.
As a workaround, cast either through an integer or through a decimal: sql server modulo float – Google Search
CAST(CAST(TheInaccurateFloatValue AS decimal(38,19)) % ModuloValue AS float)
The decimal(38,19) is the maximum non-float precision you get.
( cast(dividend as integer) % divisor ) + ( dividend - cast(dividend as integer))
–jeroen
Posted in Algorithms, Database Development, Development, Floating point handling, Software Development, SQL, SQL Server, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012, SQL Server 2014 | Leave a Comment »
Posted by jpluimers on 2016/12/07
In the continued “floating point code is hard for most software developers” series:
[WayBack] Why does the Windows calculator generate tiny errors when calculating the square root of a perfect square? – The Old New Thing
Because it doesn’t know that it’s a perfect square.
–jeroen
Posted in Algorithms, Conference Topics, Conferences, Development, Event, Floating point handling, Software Development, The Old New Thing, Windows Development | Leave a Comment »
Posted by jpluimers on 2016/11/23
Apple fanboys all know about 1 Infinite Loop. Turbo Pascal adepts about the index entries “infinite loop See loop, infinite” and “loop, infinite See infinite loop”.
Google as a more direct approach: www.google.com/search?q=recursion
Posted in Algorithms, Apple, Borland Pascal, Design Patterns, Development, Google, Pascal, Power User, Software Development, Turbo Pascal | Leave a Comment »
Posted by jpluimers on 2016/11/22
A while ago, I needed to get the various date, time and week values from WMIC to environment variables with pre-padded zeros. I thought: easy job, just write a batch file.
Tough luck: I couldn’t get the values to expand properly. Which in the end was caused by WMIC emitting UTF-16 and the command-interpreter not expecting double-byte character sets which messed up my original batch file.
| What I wanted | What I got |
|---|---|
|
|
WMIC uses this encoding because the Wide versions of Windows API calls use UTF-16 (sometimes called UCS-2 as that is where UTF-16 evolved from).
As Windows uses little-endian encoding by default, the high byte (which is zero) of a UTF-16 code point with ASCII characters comes first. That messes up the command interpreter.
Lucikly rojo was of great help solving this.
His solution is centered around set /A, which:
Enjoy and shiver with the online help extract:
Read the rest of this entry »
Posted in Algorithms, Batch-Files, Development, Encoding, Floating point handling, Scripting, Software Development, UCS-2, UTF-16, UTF16 | Leave a Comment »
Posted by jpluimers on 2016/07/20
Great explanation of Diffie-Hellman Key Exchange – YouTube.
It is based on mixing colors and some colors of the mix being private.
Brilliant!
–jeroen
Posted in Algorithms, Development, Encryption, Hashing, https, OpenSSL, Power User, Public Key Cryptography, Security, Software Development | Leave a Comment »
Posted by jpluimers on 2016/07/05
Not as bad as #brexit but still: With 3 days notice. Yay. Another timezone database fire drill. – Peter da Silva – Google+:
Additional reports concur that DST has been permanently canceled in Egypt, by both the Cabinet and the Parliament. http://www.sis.gov.eg/En/Templates/Articles/tmpArticleNews.aspx?ArtID=105572 http://english.ahram.org.eg/NewsContent/1/64/232478/Egypt/Politics-/Egypts-cabinet-abolishes-daylight-saving-time.aspx http://www.egyptindependent.com/news/cabinet-cancels-daylight-saving-time-following-parliament-vote http://www.parlmany.com/News/7/101143/- -Matt
It is already fixed in eggert/tz: Time zone database and code as mentioned in the announcement [tz] [tz-announce] 2016f release of tz code and data available
Via: With 3 days notice. Yay. Another timezone database fire drill. – Kristian Köhntopp – Google+
–jeroen
Don’t forget to watch The Problem with Time & Timezones – Computerphile – YouTube (thanks Andre Naumann)
Posted in Algorithms, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2016/05/10
The basics:
More details at How Shazam Works To Identify (Nearly) Every Song You Throw At It including this fingerprint example
Song Audio Fingerprint
–jeroen
via: How Shazam Works To Identify (Nearly) Every Song You Throw At It.
Posted in Algorithms, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2016/04/07
Very interesting read and nice GIF showing how the algorithm works: The Simple, Elegant Algorithm That Makes Google Maps Possible | Motherboard.
Second image: Sub83/Wiki
–jeroen
Posted in Algorithms, Development, Software Development | 1 Comment »
Posted by jpluimers on 2016/01/20
When everybody uses (a+b)/2 but should use sqrt((a*a+b*b)/2) or even [Wayback/Archive.is] weigh the RGB parts.
–jeroen
via: Kristian Köhntopp – Google+.
Posted in Algorithms, Color (software development), Conference Topics, Conferences, Development, Event, Software Development | Leave a Comment »
Posted by jpluimers on 2015/12/16
Interesting:
sorting in ascending order (of magnitude) usually improves things
–jeroen
via c++ – In which order should floats be added to get the most precise result? – Stack Overflow.
Posted in Algorithms, Development, Floating point handling, Software Development | Leave a Comment »
The Wiert Corner - irregular stream of stuff 