]b=: i.7 0 1 2 3 4 5 6 b^2 Squares 0 1 4 9 16 25 36 b^3 Cubes 0 1 8 27 64 125 216 b^0.5 Square roots 0 1 1.41421 1.73205 2 2.23607 2.44949The bond conjunction & can be used to bind an argument to a dyad in order to produce a corresponding defined verb. For example:
square=: ^&2 Square (power and 2) square b 0 1 4 9 16 25 36 (sqrt=: ^&0.5) b Square root function 0 1 1.41421 1.73205 2 2.23607 2.44949A left argument can be similarly bound:
Log=: 10&^. Base-10 logarithm Log 2 4 6 8 10 100 1000 0.30103 0.60206 0.778151 0.90309 1 2 3Such defined verbs can of course be used in forks. For example:
in29=: 2&< *. <&9 Interval test in29 0 1 2 5 8 13 21 0 0 0 1 1 0 0 IN29=: in29 # ] Interval selection IN29 0 1 2 5 8 13 21 5 8 LOE=: <+.= 5 LOE 3 4 5 6 7 0 0 1 1 1 integertest=: <. = ] The monad <. is floor integertest 0 0.5 1 1.5 2 2.5 3 1 0 1 0 1 0 1 int=: integertest int (i.13)%3 1 0 0 1 0 0 1 0 0 1 0 0 1
Exercises
| 7.1 | The verb # is used dyadically in the
program IN29 . Enter expressions such
as(j=: 3 0 4 0 1) # i.5 to determine the behaviour
of #, and state the result of #j#i.5 .
(Also try 1j1#i.5 .) Answer: +/j |
| 7.2 | Cover the answers on the right and apply the following programs
to lists to determine (and state in English) the purpose of each: test1=: >&10 *. <&100 Test if in 10 to 100 int=: ] = <. Test if integer test2=: int *. test1 Test if integer and in 10 to 100 test3=: int +. test1 Test if integer or in 10 to 100 sel=: test2 # ] Select integers in 10 to 100 |
| 7.3 | Cover the program definitions on the left of the
preceding exercise, and make new programs for the stated effects. |
| 7.4 | Review the use of the fix adverb in Exercises 6.4-5, and
experiment with its use on the programs of Exercise 7.2. |