System Variable IC
⎕IC - Indeterminate Control
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Z is an integer vector whose elements each control a separate aspect of how indeterminates are handled by the system. |
⎕IC←R | sets all of the values of the Indeterminate Control Vector to R. |
⎕IC←⍬ | sets all of the values of the Indeterminate Control Vector to their system default state. |
⎕IC[L]←R | sets the value(s) of the Indeterminate Control Vector indexed by L to R. |
This experimental feature attempts to collect together in one place control of various infinite and indeterminate calculations such as ÷0,
⎕IC Index (origin-0) |
Indeterminate or Infinite Calculation |
Default Result |
---|---|---|
0 | ÷0 or L÷0 for L≠0 | ∞ |
1 | ⍟0 | ¯∞ |
2 | !R for integer R<0 | DOMAIN ERROR |
3 | 0×∞ or ∞×0 | DOMAIN ERROR |
4 | 0ׯ∞ or ¯∞×0 | DOMAIN ERROR |
5 | 0÷0 | 1 |
6 | ∞÷∞ (same sign) | DOMAIN ERROR |
7 | ∞÷∞ (different sign) | DOMAIN ERROR |
8 | ∞-∞ (same sign) | DOMAIN ERROR |
9 | L|∞ for L>0 | DOMAIN ERROR |
10 | L|¯∞ for L>0 | DOMAIN ERROR |
11 | L|∞ for L<0 | DOMAIN ERROR |
12 | L|¯∞ for L<0 | DOMAIN ERROR |
13 | ¯∞|R for R>0 | ¯∞ |
14 | ∞|R for R<0 | ∞ |
15 | 0*0 | 1 |
16 | L*∞ for L≤¯1 | DOMAIN ERROR |
17 | 0*∞ | 0 |
18 | 0*¯∞ | ∞ |
19 | ±∞*0 | DOMAIN ERROR |
20 | L*R for L<0 and non-integer R | DOMAIN ERROR |
21 | 0⍟0 | 1 |
22 | 0⍟1 | DOMAIN ERROR |
23 | 1⍟0 | DOMAIN ERROR |
24 | 1⍟1 | 1 |
25 | 0∨±∞ or ±∞∨0 | LEFT |
26 | 0∧±∞ or ±∞∧0 | DOMAIN ERROR |
27 | 0⍟R for R≠0 1 | DOMAIN ERROR |
28 | L*¯∞ for ¯1 ≤ L < 0 | DOMAIN ERROR |
The values in each element of ⎕IC control the result of the calculation as follows:
⎕IC Value | Result |
---|---|
¯1 | ¯1 |
0 | 0 |
1 | 1 |
2 | DOMAIN ERROR |
3 | ∞ |
4 | ¯∞ |
5 | LEFT |
6 | RIGHT |
For example,
⎕IO←0
⎕IC
3 4 3 2 2 1 2 2 2 2 2 2 2 4 3 1 2 0 3 2 2 1 2 2 1 5 2 2 2
0÷0
1
⎕IC[5]←2
⎕IC
3 4 3 2 2 2 2 2 2 2 2 2 2 4 3 1 2 0 3 2 2 1 2 2 1 5 2 2 2
0÷0
DOMAIN ERROR
0÷0
∧
⎕IC←⍬
⎕IC
3 4 3 2 2 1 2 2 2 2 2 2 2 4 3 1 2 0 3 2 2 1 2 2 1 5 2 2 2
To set all indeterminate results to DOMAIN ERROR, use ⎕IC[]←2.
Incomplete List of Indeterminates
There may be other indeterminates not covered by this feature. Please let us know if you think there are other cases that should be included.
System Variables (A value may be assigned to these except for ⎕DM) | |||||||||
---|---|---|---|---|---|---|---|---|---|
⎕ALX | ⎕CT | ⎕DM | ⎕DT | ⎕ELX | ⎕FC | ⎕FEATURE | ⎕FPC | ⎕IC | ⎕IO |
⎕LR | ⎕LX | ⎕PP | ⎕PR | ⎕PW | ⎕RL | ⎕SA | ⎕WSID | ||
Niladic System Functions (a value cannot be assigned to these) | |||||||||
⎕A | ⎕AV | ⎕EM | ⎕ET | ⎕LC | ⎕NNAMES | ⎕NNUMS | ⎕SI | ⎕SYSID | ⎕SYSVER |
⎕T | ⎕TC | ⎕TCBEL | ⎕TCBS | ⎕TCESC | ⎕TCFF | ⎕TCHT | ⎕TCLF | ⎕TCNL | ⎕TCNUL |
⎕TS | ⎕WA | ||||||||
Monadic or dyadic system functions (a value cannot be assigned to these) | |||||||||
⎕AT | ⎕CR | ⎕DC | ⎕DFT | ⎕DL | ⎕DR | ⎕EA | ⎕EC | ⎕ERROR | ⎕ES |
⎕EX | ⎕FMT | ⎕FX | ⎕MF | ⎕NAPPEND | ⎕NC | ⎕NCREATE | ⎕NERASE | ⎕NINFO | ⎕NL |
⎕NLOCK | ⎕NREAD | ⎕NRENAME | ⎕NREPLACE | ⎕NRESIZE | ⎕NSIZE | ⎕NTIE | ⎕NUNTIE | ⎕STOP | ⎕TF |
⎕TRACE | ⎕UCS | ⎕VR | |||||||
Note that quad functions and variables (except for the ⎕A family of functions) are case insensitive |
See Also | ||
System Commands | System Variables and Functions | Operators |
Keyboard | ||||||||||||||
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