@binary_search(t:tab, v:value)
returns the index of the first element that is equal to v in the sorted tab t. The integer -1 is returned if there is no such element.

This function is faster than @find because the elements of t are known to be increasing.

See also @find, @count, @member and @occurs.

Example: 

       @fun_def p($i, $v) { return ($i > 1) && ($v % 2 == 0) }
       @find([1, 2, 3, 4], @p)  ; returns 0
@find returns the first index greather than one such that the corresponding element is a multiple of two.

       @fun_def p($i, $v) { return ($i > 1) && ($v >= "b") }
       @find("abcdefg", @p)  ; returns 2
the index 2 is returned because the "c" is the first character greather or equal to "b" such that its position is strictly greather than one (character numbering starts at zero).