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Diffstat (limited to 'kdb+.html.markdown')
| -rw-r--r-- | kdb+.html.markdown | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/kdb+.html.markdown b/kdb+.html.markdown index ae132451..76f07f7b 100644 --- a/kdb+.html.markdown +++ b/kdb+.html.markdown @@ -6,9 +6,8 @@ contributors: filename: learnkdb.q --- -The q langauge and its database component kdb+ were developed by Arthur -Whitney and released by Kx systems in 2003. q is a descendant of -[APL](https://en.wikipedia.org/wiki/APL_(programming_language)) and as such is +The q langauge and its database component kdb+ were developed by Arthur Whitney +and released by Kx systems in 2003. q is a descendant of APL and as such is very terse and a little strange looking for anyone from a "C heritage" language background. Its expressiveness and vector oriented nature make it well suited to performing complex calculations on large amounts of data (while also @@ -69,7 +68,7 @@ at jonny.press@aquaq.co.uk / And exponentiation... 2 xexp 4 / => 16 -/ ...and rounding... +/ ...and truncating... floor 3.14159 / => 3 / ...getting the absolute value... @@ -312,7 +311,7 @@ d:`a`b`c!1 2 3 / the keyword key returns the first list key d / => `a`b`c / and value the second -value / => 1 2 3 +value d / => 1 2 3 / Indexing is indentical to lists / with the first list as a key instead of the position @@ -698,7 +697,7 @@ first each (1 2 3;4 5 6;7 8 9) / their behaviour differs based on the number of arguments the function they / are modifying receives. Here I'll summarise some of the most useful cases / a single argument function modified by scan given 2 args behaves like "do" -{x * 2}\[5;1] / => 1 2 4 8 16 3 (i.e. multiply by 2, 5 times) +{x * 2}\[5;1] / => 1 2 4 8 16 32 (i.e. multiply by 2, 5 times) {x * 2}/[5;1] / => 32 (using over only the final result is shown) / If the first argument is a function, we have the equivalent of "while" |