## Solution to APL Crossword from 15.3

## Crossword from 15.4

**Across**

1. `V[I]×B[(1+½B)-I]`

for `I`

from 1 to `½V`

, for origin 1 with `(½B)=(½V)`

5. A random integer from 0 to 4, with 0 half as likely as the others

11. `¼(½V)+(½B)`

13. The matrix `F`

with its first `M5`

columns made last

14. The values in `A`

rounded to the nearest integer (.5 down not up)

15. Are all the elements of the vector `VN`

larger than zero?

16. The difference of 102 and one-fifth `S`

18. `(V¬25)/V`

20. Flag the 52s in `N`

21. Get outta here!

22. `0`

where `S=V`

, `1`

where `S>V`

, `¯1`

where `S<V`

24. `2²'(0—A÷B)×C'~'ABC×',•0`

25. The index of the first row of the matrix `M`

that CONTAINS the vector V

27. The number of rows and columns in `K`

28. The vector `1 2 3 ... L`

29. `(RV-1),(RV-2),...,(RV-(10+VC))`

30. An empty vector with the same datatype as the scalar `S`

32. Random one-element vector from `¯1`

to `¯9`

33. Get objects from a stored workspace IF they’re not in the active workspace

35. All but the first `N`

elements of the vector `V`

36. The number of dimensions in `A`

37. Deal a card from the deck

39. Famous earless APL programmer, _______ Van Go To

40. Deal five cards from the deck

**Down**

1. `(”V)[ŒIO]`

2. Is the vector `A`

nonempty?

3. Subtract 12 from each element of `V`

; then reverse their order

4. Stick onto matrix `B`

a new column, using the numbers in the vector `VR`

divided by 20

6. The index of the first row of the matrix `M`

that MATCHES the vector `V`

7. Five random numbers from 1 to 25, with replacement

8. `2÷109÷(9‡V),9†V if (½V)‰9`

9. The available programs

10. The vector `KC`

with negative values replaced by zero and padded to length 500

12. A good name for a function that bombs a lot

17. `M+Y-N`

without using `+`

19. For a bit vector `A`

, where `L„½A`

, reshape bits `I`

to length `P`

, pad to the length of
`A`

, and compare A to see where neither is true

21. `…((½V)=0)/L5`

23. Flag the occurrences of the (start of) substring `S`

in the vector `V`

25. The first element of any nonempty array `V`

, as a scalar

26. The vector `1 2 3...`

up to some random number between 1 and 55

31. Cumulative reduction

34. What the circle `±`

function is easy as

37. A random integer scalar from 1 to `T`

38. `•–²'2*5'`

Reprinted with kind permission from Zark APL Tutor News, a quarterly publication of Zark Incorporated, 23 Ketchbrook Lane, Ellington, CT06029, USA