signum

signum x    signum[x]

Where x (or its underlying value for temporals) is

• null or negative, returns -1i
• zero, returns 0i
• positive, returns 1i

q)signum -2 0 1 3
-1 0 1 1i

q)signum (0n;0N;0Nt;0Nd;0Nz;0Nu;0Nv;0Nm;0Nh;0Nj;0Ne)
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1i

q)signum 1999.12.31
-1i

Find counts of price movements by direction:

select count i by signum deltas price from trade

Implicit iteration

signum is an atomic function.

q)signum(10;-20 30)
1i
-1 1i

q)k:`k xkey update k:`abc`def`ghi from t:flip d:`a`b!(10 -21 3;4 5 -6)

q)signum d
a| 1 -1 1
b| 1 1  -1

q)signum t
a  b
-----
1  1
-1 1
1  -1

q)signum k
k  | a  b
---| -----
abc| 1  1
def| -1 1
ghi| 1  -1

Domain and range

domain b g x h i j e f c s p m d z n u v t
range  i . i i i i i i i . i i i i i i i i

Range: i

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abs
Mathematics