2.1 Goals

That the material must be of the highest quality -- authoritative and validated -- should go without saying. We aim to produce a book, a web site with extensive search capabilities and a CD-ROM version. The material must therefore adapt to various media.

Clearly, the electronic formats must provide search capabilities. And since the DLMF is primarily mathematics with little text, providing a traditional search for the textual components will not be enough. We must provide the capability to search for formulas that match a user's criteria as well; searching for formulas according to keywords or properties of the formula: e.g. `addition theorem for elliptic functions'. More intriguing would be searches using mathematical patterns. These should be flexible regarding syntax, not restricted to TEX[8], say. And the matching process must understand the basic properties of commutativity, associativity and so forth.

Along with search capabilities, it would be extremely useful to be able to extract virtual documents. For example, one might wish to create a page of addition theorems, or a short booklet of differential equations of certain classes. Thus one must not only find pages, but collections of document fragments and formulas, and synthesize a document from them. These, along with existing sections or subsections should be viewable in a screen friendly format, or printable.

The DLMF should provide layers of detail. Beyond the dry, telegraphic, front facade of the identities, there should be associated with most elements additional metadata. This data would point to references, original sources, or short tracts going into extra detail or more esoterica.

Often one finds a formula not quite in the terms one needs and one would like to transform the expressions. It would be exciting, from within the online book, to substitute variables, or rearrange an expression, to acquire exactly the identity required. One may need to re-expand, apply transformations, other identities, .... Transformed or not, users will likely want to copy the formula into their own documents, graphics programs or computer algebra system, without loss of meaning.

For some people, a differential equation tells them all they need to know about a special function. Other, more visually oriented people, will need interactive graphics to explore the function in different regions, on different scales. Graphics in 2D and 3D (or more) will be needed. Above all, these graphics must be `Honest' in the sense of Fateman [5]: they must not display artificial flat planes where clipped, nor smooth over narrow features, nor succumb to other sampling errors.