cos, acos

Cosine, arccosine

cos x     cos[x]
acos x    acos[x]

Where x is a numeric, returns

cos

the cosine of x, taken to be in radians. The result is between -1 and 1, or null if the argument is null or infinity.

acos

the arccosine of x; that is, the value whose cosine is x. The result is in radians and lies between 0 and π. (The range is approximate due to rounding errors). Null is returned if the argument is not between -1 and 1.

q)cos 0.2                       / cosine
0.9800666
q)min cos 10000?3.14159265
-1f
q)max cos 10000?3.14159265
1f

q)acos -0.4                     / arccosine
1.982313

Implicit iteration

cos and acos are atomic functions.

q)cos (.2;.3 .4)
0.9800666
0.9553365 0.921061

q)acos (.2;.3 .4)
1.369438
1.266104 1.159279