My name is Aaron Hsu, and I'm a computer scientist. I'm changing the way people look at computing and programming languages, what they can do with them, and how they do it.
Scalar functions perform most of the hard labor in an APL program. A scalar function defines a mapping from one or two scalar values to a third value. In math, the addition function maps two numbers to their sum. Many other such functions exist. The following table gives all the
Previous sessions established a basic conception of indexing an array. Namely, an index encodes a reference to an element in an array according to the position of the element along each of its dimensions. Always a vector, each element of an index falls in the range [0, d) where d
By now, clearly a shape and vector of values precisely determines an array. All APL functions operate over arrays; they describe new arrays in terms of its arguments. What about describing a sub-array of another array? Indexing provides a means of identifying specific elements of an array. Some people might
An array that only describes a box which may contain elements, but that does not contain any elements, does not mean much. While shapes help to clarify the APL language, when doing any work, they really only describe how to arrange the elements of an array. The monadic ravel function
Arrays arrange data into a certain rectangular shape. In APL, the shape of an array is a vector --- yes, in APL, shapes are also arrays --- that describes the number and size of layout in terms of dimensions. All arrays have a shape; if A is an array then