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char — produce character
entab — replace blanks by tabs
map — map characters
name — produce name
ord — produce ordinal
repl — replicate string
reverse — reverse string
s<<=s — lexically less than or equal
s<<s — lexically less than
s==s — lexically equal
s>>=s — lexically greater than or equal
s>>s — lexically greater than
string — convert to string
s||s — concatenate strings
s~==s — lexically not equal
trim — trim string
type — produce type name
x[i+:i] — produce substring or list section
x[i-:i] — produce substring or list section
x[i:i] — produce substring or list section
x[x, …] — multiple subscript
x[x] — subscript

Index of Function Types:
affects &pos
character sets
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control structures
file processing
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Index of Subsystems:
base
digitcnt.icn
SNOBOL4 functions
basemath
acos
 
compute arc cosine
 
Description

r2 acos(r1)
acos(r1) produces the arc cosine of r1 in the range of 0 to π for r1 in the range of –1 to 1.
 
Parameters
r1
real
returns
arc cosine of r1.
 
Errors
102 r1 is not real
205 |r1| is greater than 1