Category Archives: Q

Matrix operations in Q/KDB+

Posted on March 1, 2012 by novieq

1) Find the maximum element of each column in matrix m. max m 2) Find the minimum element of each row of a matrix m. min each x. 3) Test for symetric matrix m~flip m 4) Test for anti-symetric matrix … Continue reading →

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Alternative Solution : Q Idioms 31

Posted on February 29, 2012 by novieq

x:”egg” y:”mrin” g:1 0 1 0 1 1 0 Solution Posted :  (x,y)[rank g] “merging” Alternative Solution : (y,x)[iasc idesc g]

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Greatest Common Divisor in Q/KDB+

Posted on February 29, 2012 by novieq

Euclid’s algorithm : Recursive definition of the gcd function using Euclid’s algorithm is : function gcd(a, b) { if (b = 0) return a else return gcd(b, a mod b) } Solution in Q : g:{$[y=0;:x;:g[y;x mod y]];} Results : … Continue reading →

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Subvector grade down – Q Idioms 15

Posted on February 29, 2012 by novieq

x:1 0 0 1 0 0 1 0 y:14 12 18 15 13 16 11 17 K solution : {,/x+’>:’x _ y}[&x;y] 2 0 1 5 3 4 7 6 Solution Posted : {raze x +’ idesc each x _ … Continue reading →

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Subvector grade up – QIdiom 7

Posted on February 29, 2012 by novieq

x:1 0 0 1 0 0 1 0 y:14 12 18 16 13 15 11 17 Solution in K : {,/x+'<:’x _ y}[&x;y] 1 0 2 4 3 5 6 7 Solution Posted : {raze x +’ iasc each x … Continue reading →

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Factorial Program

Posted on February 29, 2012 by novieq

Q Solution 1:  factorial:{prd 1+til x} Q Solution 2: n:5 do[-1+f:r:n;r*:f-:1] r 120 The solution 2 is referred from Execution Control chapter in Q for Mortals. Results : factorial[5] 120

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Hello world!

Posted on February 23, 2012 by novieq

q)s:`Hello`World; q)s `Hello`World

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