System Variable IC
From NARS2000
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. |
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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 Calculation |
Default Result |
---|---|---|
0 | ÷0 | ∞ |
1 | ⍟0 | ¯∞ |
2 | !N for integer N<0 | DOMAIN ERROR |
3 | 0×∞ and ∞×0 | DOMAIN ERROR |
4 | 0ׯ∞ and ¯∞×0 | DOMAIN ERROR |
5 | 0÷0 | 1 |
6 | ∞÷∞ (same sign) | DOMAIN ERROR |
7 | ∞÷∞ (different sign) | DOMAIN ERROR |
8 | 0*0 | 1 |
9 | N*∞ for integer N≤¯1 | DOMAIN ERROR |
10 | 0⍟0 | DOMAIN ERROR |
11 | 0⍟1 | DOMAIN ERROR |
12 | 1⍟0 | DOMAIN ERROR |
13 | 1⍟1 | 1 |
The values in each element of ⎕IC control the result of the calculation as follows:
⎕IC Value | Result |
---|---|
0 | 0 |
1 | 1 |
2 | DOMAIN ERROR |
3 | ∞ |
4 | ¯∞ |
For example,
⎕IO←0
⎕IC
3 4 2 2 2 1 2 2 1 2 2 2 2 1
0÷0
1
⎕IC[5]←2
0÷0
DOMAIN ERROR
0÷0
∧
⎕IC←⍬
⎕IC
3 4 2 2 2 1 2 2 1 2 2 2 2 1
Incomplete List of Indeterminates
That there may be other indeterminates not covered by this feature. Please let us know if you think there are other cases which should be included.