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% *********************************************************************
\head{chapter}{Browse}{ugBrowse}
% *********************************************************************

This chapter discusses the \Browse{}
\index{Browse@\Browse{}}
component of \HyperName{}.
\index{HyperDoc@{\HyperName{}}}
We suggest you invoke \Language{} and work through this
chapter, section by section, following our examples to gain some
familiarity with \Browse{}.

% *********************************************************************
\head{section}{The Front Page: Searching the Library}{ugBrowseStart}
% *********************************************************************
To enter \Browse{}, click on {\bf Browse} on the top level page
of \HyperName{} to get the {\it front page} of \Browse{}.
%
\includehyperdoc{h-brfront}{The Browse front page.}

To use this page, you first enter a \spadgloss{search string} into
the input area at the top, then click on one of the buttons below.
We show the use of each of the buttons by example.

\subsubsection{Constructors}

First enter the search string {\tt Matrix} into the input area and
click on {\bf Constructors}.
What you get is the {\it constructor page} for \spadtype{Matrix}.
We show and describe this page in detail in
\spadref{ugBrowseDomain}.
By convention, \Language{} does a case-insensitive search for a
match.
Thus {\tt matrix} is just as good as {\tt Matrix}, has the same
effect as {\tt MaTrix}, and so on.
We recommend that you generally use lowercase letters for names
however.
A search string with only capital letters has a special meaning
(see \spadref{ugBrowseCapitalizationConvention}).


Click on \UpBitmap{} to return to the \Browse{} front page.

Use the symbol ``{\tt *}'' in search strings as a \spadgloss{wildcard}.

A wildcard matches any substring, including the empty string.
For example, enter the search string {\tt *matrix*} into the input
area and click on {\bf Constructors}.\footnote{To get only
categories, domains, or packages, rather than all constructors,
you can click on the corresponding button to the right of {\bf
Constructors}.}
What you get is a table of all constructors whose names contain
the string ``{\tt matrix}.''

\includehyperdoc{h-consearch}{Table of exposed constructors matching {\tt *matrix*}.}

%% Following para replaced 1995oct30 MGR
%These are all the \spadglossSee{exposed}{expose} constructors in
%\Language{}.
%To see how to get all exposed and unexposed constructors in
%\Language{}, skip to the section entitled {\bf Exposure} in
%\spadref{ugBrowseOptions}.
All constructors containing the string are listed, whether
\spadglossSee{exposed}{expose} or \spadglossSee{unexposed}{expose}.
You can hide the names of the unexposed constructors by clicking
on the {\it *=}{\bf unexposed} button in the {\it Views} panel at
the bottom of the window.
(The button will change to {\bf exposed} {\it only}.)

One of the names in this table is \spadtype{Matrix}.
Click on \spadtype{Matrix}.
What you get is again the constructor page for \spadtype{Matrix}.
As you see, \Browse{} gives you a large network of
information in which there are many ways to reach the same
pages.
\exptypeindex{Matrix}

Again click on the \UpBitmap{} to return to the table of constructors
whose names contain {\tt matrix}.
%Below the table is a {\bf Views} panel. % here & globally MGR 1995oct30
Below the table is a {\it Views} panel.
This panel contains buttons that let you view constructors in different
ways.
To learn about views of constructors, skip to
\spadref{ugBrowseViewsOfConstructors}.

Click on \UpBitmap{} to return to the \Browse{} front page.

\subsubsection{Operations}

Enter {\tt *matrix} into the input area and click on {\bf
Operations}.
This time you get a table of {\it operations} whose names end with {\tt
matrix} or {\tt Matrix}.

\includehyperdoc{h-matrixops}{Table of operations matching {\tt *matrix}.}

If you select an operation name, you go to a page describing all
the operations in \Language{} of that name.
At the bottom of an operation page is another kind of {\it Views} panel,
one for operation pages.
To learn more about these views, skip to
\spadref{ugBrowseViewsOfOperations}.

Click on \UpBitmap{} to return to the \Browse{} front page.

\subsubsection{General}

This button does a general search for all constructor and operation
names matching the search string.
Enter the search string \allowbreak
{\tt *matrix*} into the input area.
Click on {\bf General} to find all constructs that have {\tt
matrix} as a part of their name.

\includehyperdoc{h-gensearch}{Table of all constructs matching {\tt *matrix*}.}

The summary gives you all the names under a heading when the number of
entries is less than 10. % "less than 10." replaces the following:
                         % sufficiently small%\footnote{See
%\spadref{ugBrowseOptions} to see how you can change this.}.
%% MGR 1995oct31

Click on \UpBitmap{} to return to the \Browse{} front page.

\subsubsection{Documentation}

Again enter the search key {\tt *matrix*} and this time click on
{\bf Documentation}.
This search matches any constructor and operation
name whose documentation contains a substring matching {\tt
matrix}.

\includehyperdoc{h-docsearch}{Table of constructs with documentation matching {\tt *matrix*}.}

Click on \UpBitmap{} to return to the \Browse{} front page.

\subsubsection{Complete}

This search combines both {\bf General} and {\bf Documentation}.

\includehyperdoc{h-comsearch}{Table summarizing complete search for pattern {\tt *matrix*}.}

% *********************************************************************
\head{section}{The Constructor Page}{ugBrowseDomain}
% *********************************************************************

In this section we look in detail at a constructor page for domain
\spadtype{Matrix}.
Enter {\tt matrix} into the input area on the main \Browse{} page
and click on {\bf Constructors}.

\includehyperdoc{h-matpage}{Constructor page for \protect\spadtype{Matrix}.}


The header part tells you that \spadtype{Matrix} takes
one argument called {\tt R} that must be a
domain of category \spadtype{AbelianMonoid}.
Just what domains can be arguments of \spadtype{Matrix}?
To find this out, click on the {\tt R} on the second line of the
heading.
What you get is a table of all acceptable domain parameter values
of {\tt R}, or a table of \spadgloss{abelian monoids} in \Language{}.

\includehyperdoc{h-matargs}{Table of acceptable domain parameters to \protect\spadtype{Matrix}.}

Click on \UpBitmap{} to return to the constructor page for
\spadtype{Matrix}.
\texht{\newpage}{}

There is also a brief description of constructor \spadtype{Matrix}
and its abbreviation \spadtype{MATRIX}.

If you have access to the source code of \Language{},
\index{source code}
this header part also gives you the name of the source file
containing the definition of \spadtype{Matrix}.
Click on it to pop up an editor window containing the source code
of \spadtype{Matrix}.

\includehyperdoc{h-matsource}{Source code for \protect\spadtype{Matrix}.}

We recommend that you leave the editor window up while working
through this chapter as you occasionally may want to refer to it.
\texht{\newpage}{}

% *********************************************************************
\head{subsection}{Constructor Page Buttons}{ugBrowseDomainButtons}
% *********************************************************************

We examine each button on this page in order.

\subsubsection{Operations}

Click here to get a table of operations exported by
\spadtype{Matrix}.
You may wish to widen the window to have multiple columns as
below.

\includehyperdoc{h-matops}{Table of operations from \protect\spadtype{Matrix}.}

If you click on an operation name, you bring up a description
page for the operations.
For a detailed description of these pages, skip to
\spadref{ugBrowseViewsOfOperations}.

\subsubsection{Examples}

Click here to get an {\it examples page} with examples of operations to
create and manipulate matrices.

\includehyperdoc{h-matexamp}{Example page for \protect\spadtype{Matrix}.}

Read through this section.
Try selecting the various buttons.
Notice that if you click on an operation name, such as
\spadfunFrom{new}{Matrix}, you bring up a description page for that
operation from \spadtype{Matrix}.

Example pages have several examples of \Language{} commands.
Each example has an active button to its left.
Click on it!
A pre-computed answer is pasted into the page immediately following the
command.
If you click on the button a second time, the answer disappears.
This button thus acts as a toggle:
``now you see it; now you don't.''

Note also that the \Language{} commands themselves are active.
If you want to see \Language{} execute the command, then click on it!
A new \Language{} window appears on your screen and the command is
executed.

\begin{htonly}
At the end of the page is generally a menu of buttons that lead
you to further sections.
Select one of these topics to explore its contents.
\end{htonly}

\subsubsection{Exports}

Click here to see a page describing the exports of \spadtype{Matrix}
exactly as described by the source code.

\includehyperdoc{h-matexports}{Exports of \protect\spadtype{Matrix}.}

As you see, \spadtype{Matrix} declares that it exports all the operations
and categories exported by category
\spadtype{MatrixCategory(R, Row, Col)}.
In addition, two operations, \spadfun{diagonalMatrix} and
\spadfun{invertIfCan}, are explicitly exported.

To learn a little about the structure of \Language{}, we suggest you do
the following exercise.
\begin{texonly}
Otherwise, go on to the next section.
\end{texonly}
\begin{htonly}
Otherwise, click on \UpButton{} and go on to the next section.
\end{htonly}
\spadtype{Matrix} explicitly exports only two operations.
The other operations are thus exports of \spadtype{MatrixCategory}.
In general, operations are usually not explicitly exported by a domain.
Typically they are \spadglossSee{inherited}{inherit} from several
different categories.
Let's find out from where the operations of \spadtype{Matrix} come.

\begin{enumerate}
\item Click on {\bf MatrixCategory}, then on {\bf Exports}.
Here you see that {\bf MatrixCategory} explicitly exports many matrix
operations.
Also, it inherits its operations from
\spadtype{TwoDimensionalArrayCategory}.

\item Click on {\bf TwoDimensionalArrayCategory}, then on {\bf Exports}.
Here you see explicit operations dealing with rows and columns.
In addition, it inherits operations from
\spadtype{HomogeneousAggregate}.

\item Click on \UpBitmap{} repeatedly to return to the constructor page
for \spadtype{Matrix}.

\end{enumerate}

\subsubsection{Parents}

The parents of a domain are the same as the categories mentioned under
the {\bf Exports} button on the first page.
Domain \spadtype{Matrix} has two parents but in general a domain can
have any number.

\subsubsection{Ancestors}

The \spadglossSee{ancestors}{ancestor} of a constructor consist of its parents, the
parents of its parents, and so on.
Did you perform the exercise in the last section under {\bf Exports}?
If so, you  see here all the categories you found while ascending the
{\bf Exports} chain for \spadtype{Matrix}.

\subsubsection{Dependents}

The \spadglossSee{dependents}{dependent} of a constructor are those
\spadglossSee{domains}{domain} or \spadglossSee{packages}{package}
that mention that
constructor either as an argument or in its \spadglossSee{exports}{export}.

If you click on {\bf Dependents} two entries may surprise you:
\spadtype{RectangularMatrix} and \spadtype{SquareMatrix}.
This happens because \spadtype{Matrix}, as it turns out, appears in
signatures of operations exported by these domains.

\subsubsection{Search Path}

The term \spadgloss{search path} refers to the {\it search order} for
functions.
If you are an expert user or curious about how the \Language{} system
works, try the following exercise.
Otherwise, you best skip this button and go on to {\bf Users}.

Clicking on {\bf Search Path} gives you a
list of domain constructors:
\spadtype{InnerIndexedTwoDimensionalArray},
\aliascon{MatrixCategory&}{MATCAT-},
\aliascon{TwoDimensionalArrayCategory&}{ARR2CAT-},
\aliascon{HomogeneousAggregate&}{HOAGG-},
\aliascon{Aggregate&}{AGG-},
\aliascon{Evalable&}{EVALAB-},
\aliascon{SetCategory&}{SETCAT-},
\aliascon{Hashable&}{HASHABL-},
\aliascon{InnerEvalable&}{IEVALAB-},
\aliascon{BasicType&}{BASTYPE-}.
What are these constructors and how are they used?

We explain by an example.
Suppose you create a matrix using the interpreter, then ask for its
\spadfun{rank}.
\Language{} must then find a function implementing the \spadfun{rank}
operation for matrices.
The first place \Language{} looks for \spadfun{rank} is in the \spadtype{Matrix}
domain.

If not there, the search path of \spadtype{Matrix} tells \Language{} where
else to look.
Associated with the matrix domain are ten other search path domains.
Their order is important.
\Language{} first searches the first one,
\spadtype{InnerIndexedTwoDimensionalArray}.
If not there, it searches the second \aliascon{MatrixCategory&}{MATCAT-}.
And so on.

Where do these {\it search path constructors} come from?
The source code for \spadtype{Matrix} contains this syntax for the
\spadgloss{function body} of
\spadtype{Matrix}:\footnote{\spadtype{InnerIndexedTwoDimensionalArray}
is a special domain implemented for matrix-like domains to provide
efficient implementations of \twodim{} arrays.
For example, domains of category \spadtype{TwoDimensionalArrayCategory}
can have any integer as their \spad{minIndex}.
Matrices and other members of this special ``inner'' array have their
\spad{minIndex} defined as \spad{1}.}
\begin{verbatim}
InnerIndexedTwoDimensionalArray(R,mnRow,mnCol,Row,Col)
   add ...
\end{verbatim}
where the ``{\tt ...}'' denotes all the code that follows.
In English, this means:
``The functions for matrices are defined as those from
\spadtype{InnerIndexedTwoDimensionalArray} domain augmented by those
defined in `{\tt ...}','' where the latter take precedence.

This explains \spadtype{InnerIndexedTwoDimensionalArray}.
The other names, those with names ending with an ampersand \spadSyntax{&} are
\spadglossSee{default packages}{default package}
for categories to which \spadtype{Matrix} belongs.
Default packages are ordered by the notion of ``closest ancestor.''

\subsubsection{Users}

A user of \spadtype{Matrix} is any constructor that uses
\spadtype{Matrix} in its implementation.
For example, \spadtype{Complex} is a user of \spadtype{Matrix}; it
exports several operations that take matrices as arguments or return
matrices as values.\footnote{A constructor is a user of
\spadtype{Matrix} if it handles any matrix.
For example, a constructor having internal (unexported) operations
dealing with matrices is also a user.}

\subsubsection{Uses}

A \spadgloss{benefactor} of \spadtype{Matrix} is any constructor that
\spadtype{Matrix} uses in its implementation.
This information, like that for clients, is gathered from run-time
structures.\footnote{The benefactors exclude constructors such as
\spadtype{PrimitiveArray} whose operations macro-expand and so vanish
from sight!}

Cross reference pages for categories have some different buttons on
them.
Starting with the front page of \Browse{}, search for
\spadtype{Ring} and enter its constructor page.
Here are buttons {\bf Parents} and {\bf Ancestors} similar to the notion
for domains, except for categories the relationship between parent and
child is defined through \spadgloss{category extension}.

\subsubsection{Children}

Category hierarchies go both ways.
There are children as well as parents.

\subsubsection{Descendants}

These are children, children of children, and so on.

Category hierarchies are complicated by the fact that categories take
parameters.
Where a parameterized category fits into a hierarchy {\it may} depend on
values of its parameters.
In general, the set of categories in \Language{} forms a {\it directed
acyclic graph}, that is, a graph with directed arcs and no cycles.

\subsubsection{Domains}

This produces a table of all domain constructors that can possibly be
rings (members of category \spadtype{Ring}).
Some domains are unconditional rings.
Others are rings for some parameters and not for others.
To find out which, select the {\bf conditions} button in the views
panel.
For example, \spadtype{DirectProduct(n, R)} is a ring if {\tt R} is a
ring.



% *********************************************************************
\head{subsection}{Views Of Constructors}{ugBrowseViewsOfConstructors}
% *********************************************************************

Below every constructor table page is a {\it Views} panel.
As an example, click on {\bf Uses} from
the constructor page of \spadtype{Matrix} to produce a
short table of constructor names.

The {\it Views} panel is at the bottom of the page.
Two items, {\it names} and {\it conditions,} are in italics.
Others are active buttons.
The active buttons are those that give you useful alternative views
on this table of constructors.
Once you select a view, you notice that the button turns
off (becomes italicized) so that you cannot reselect it.

\subsubsection{names}

This view gives you a table of names.
Selecting any of these names brings up the constructor page for that
constructor.

\subsubsection{abbrs}

This view gives you a table of abbreviations, in the same order as the
original constructor names.
Abbreviations are in capitals and
they can be used interchangeably with constructor names in input areas.

\subsubsection{kinds}

This view organizes constructor names into
the three kinds: categories, domains and packages.

\subsubsection{parameters}

This view presents constructors with the arguments.
This view of the benefactors of \spadtype{Matrix} shows that
\spadtype{Matrix} uses as many as ten different \spadtype{List} domains
in its implementation.

\subsubsection{filter}

This button is used to refine the list of names or abbreviations.
Starting with the {\it names} view, enter {\tt m*} into the input area
and click on {\bf filter}.
You then get a shorter table with only the names beginning with {\tt m}.

\subsubsection{descriptions}

This gives you documentation for each of the constructors.

\subsubsection{conditions}

This page organizes the constructors according to predicates.
The view is not available for your example page since all constructors
are unconditional.
For a table with conditions, return to the {\bf Ancestors} page
for \spadtype{Matrix}, click on {\bf conditions} in the view panel.
This page shows you that \spadtype{CoercibleTo(OutputForm)} and
\spadtype{SetCategory} are ancestors of \spadtype{Matrix(R)} only if {\tt R}
belongs to category \spadtype{SetCategory}.

%*********************************************************************
\head{subsection}{Giving Parameters to Constructors}{ugBrowseGivingParameters}
%*********************************************************************

Notice the input area at the bottom of the constructor page.
If you leave this blank, then the information you get is for the
domain constructor \spadtype{Matrix(R)}, that is, \spadtype{Matrix} for an
arbitrary underlying domain {\tt R}.

In general, however, the exports and other information {\it do} usually
depend on the actual value of {\tt R}.
For example, \spadtype{Matrix} exports the \spadfun{inverse} operation
only if the domain {\tt R} is a \spadtype{Field}.
To see this, try this from the main constructor page:

\begin{enumerate}
\item Enter {\tt Integer} into the input area at the bottom of the page.

\item Click on {\bf Operations}, producing a table of operations.
Note the number of operation names that appear at the top of the
page.

\item Click on \UpBitmap{} to return to the constructor page.

\item Use the
\texht{\fbox{\bf Delete}}{{\bf Delete}}
or
\texht{\fbox{\bf Backspace}}{{\bf Backspace}}
keys to erase {\tt Integer} from the input area.

\item Click on {\bf Operations} to produce a new table of operations.
Look at the number of operations you get.
This number is greater than what you had before.
Find, for example, the operation \spadfun{inverse}.

\item Click on {\bf inverse} to produce a page describing the operation
\spadfun{inverse}.
At the bottom of the description, you notice that the {\bf
Conditions} line says ``{\tt R} has \spadtype{Field}.''
This operation is {\it not} exported by \spadtype{Matrix(Integer)} since
\spadtype{Integer} is not a \spadgloss{field}.

Try putting the name of a domain such as \spadtype{Fraction Integer}
(which is a field) into the input area, then clicking on {\bf Operations}.
As you see, the operation \spadfun{inverse} is exported.
\end{enumerate}

% *********************************************************************
\head{section}{Miscellaneous Features of Browse}{ugBrowseMiscellaneousFeatures}
% *********************************************************************
% *********************************************************************
\head{subsection}{The Description Page for Operations}{ugBrowseDescriptionPage}
% *********************************************************************
From the constructor page of \spadtype{Matrix},
click on {\bf Operations} to bring up the table of operations
for \spadtype{Matrix}.

Find the operation {\bf inverse} in the table and click on it.
This takes you to a page showing the documentation for this operation.

\includehyperdoc{h-matinv}{Operation \protect\spadfunFrom{inverse}{Matrix} from \protect\spadtype{Matrix}.}

Here is the significance of the headings you see.

\subsubsection{Arguments}

This lists each of the arguments of the operation in turn, paraphrasing
the \spadgloss{signature} of the operation.
As for signatures, a \spadSyntax{%} is used to designate {\em this domain},
that is, \spadtype{Matrix(R)}.

\subsubsection{Returns}

This describes the return value for the operation, analogous to the {\bf
Arguments} part.

\subsubsection{Origin}

This tells you which domain or category explicitly exports the
operation.
In this example, the {\it Origin} is \spadtype{MatrixCategory}.


\subsubsection{Conditions}

This tells you that the operation is exported by \spadtype{Matrix(R)} only if
``{\tt R} has \spadtype{Field},'' that is, ``{\tt R} is a member of
category \spadtype{Field}.''
When no {\bf Conditions} part is given, the operation is exported for
all values of {\tt R}.

\subsubsection{Description}

Here are the \spadSyntax{++} comments
that appear in the source code of its {\it Origin}, here \spadtype{Matrix}.
You find these comments in the source code for \spadtype{Matrix}.

\includehyperdoc{h-matmap}{Operations \protect\spadfun{map} from \protect\spadtype{Matrix}.}

Click on \UpBitmap{} to return to the table of operations.
Click on {\bf map}.
Here you find three different operations named \spadfun{map}.
This should not surprise you.
Operations are identified by name and \spadgloss{signature}.
There are three operations named \spadfun{map}, each with
different signatures.
What you see is the {\it descriptions} view of the operations.
If you like, select the button in the heading of one of these
descriptions to get {\it only} that operation.

\subsubsection{Where}

This part qualifies domain parameters mentioned in the arguments to the
operation.

% *********************************************************************
\head{subsection}{Views of Operations}{ugBrowseViewsOfOperations}
% *********************************************************************

We suggest that you go to the constructor page for \spadtype{Matrix}
and click on {\bf Operations} to bring up a table of operations
with a {\it Views} panel at the bottom.

\subsubsection{names}

This view lists the names of the operations.
Unlike constructors, however, there may be several operations with the
same name.
The heading for the page tells you the number of unique names and the
number of distinct operations when these numbers are different.

\subsubsection{filter}

As for constructors, you can use this button to cut down the list of
operations you are looking at.
Click on {\bf filter} and enter, for example, {\tt m*} into the
input area, then click on {\bf filter}.
As usual, any logical expression is permitted.
For example, use
\begin{verbatim}
*! or *?
\end{verbatim}
to get a list of destructive operations and predicates.

\subsubsection{descriptions}

This gives you the most information:
a detailed description of all the operations in the form you have seen
before.
Every other button summarizes these operations in some form.

\subsubsection{signatures}

This views the operations by showing their signatures.

\subsubsection{parameters}

This views the operations by their distinct syntactic forms with
parameters.

\subsubsection{origins}

This organizes the operations according to the constructor that
explicitly exports them.

\subsubsection{conditions}

This view organizes the operations into conditional and unconditional
operations.

\subsubsection{usage}

This button is only available if your user-level is set to {\it
\index{user-level}
development}.
The {\bf usage} button produces a table of constructors that reference this
operation.\footnote{\Language{} requires an especially long time to
produce this table, so anticipate this when requesting this
information.}

\subsubsection{implementation}

This button is only available if your user-level is set to {\it
development}.
\index{user-level}
If you enter values for all domain parameters on the constructor page,
then the {\bf implementation} button can be clicked.
This button tells you what domains or packages actually implement the
various operations.\footnote{This button often takes a long time; expect
a delay while you wait for an answer.}

With your user-level set to {\it development}, we suggest you try this
exercise.
Return to the main constructor page for \spadtype{Matrix}, then enter
{\tt Integer} into the input area at the bottom as the value of {\tt R}.
Then click on {\bf Operations} to produce a table of operations.
Click on {\bf implementation}.
After some delay, you get a page describing what implements each of
the matrix operations, organized by the various domains and packages.

\includehyperdoc{h-matimp}{Implementation domains for \protect\spadtype{Matrix}.}

\texht{\newpage}{}

% *********************************************************************
\head{subsection}{Capitalization Convention}{ugBrowseCapitalizationConvention}
% *********************************************************************

When entering search keys for constructors, you can use capital
letters to search for abbreviations.
For example, enter {\tt UTS} into the input area and click on {\bf
Constructors}.
Up comes a page describing \spadtype{UnivariateTaylorSeries}
whose abbreviation is \spadtype{UTS}.

Constructor abbreviations always have three or more capital
letters.
For short constructor names (six letters or less), abbreviations
are not generally helpful as their abbreviation is typically the
constructor name in capitals.
For example, the abbreviation for \spadtype{Matrix} is
\spadtype{MATRIX}.

Abbreviations can also contain numbers.
For example, \spadtype{POLY2} is the abbreviation for constructor
\spadtype{PolynomialFunctions2}.
For default packages, the abbreviation is the same as the
abbreviation for the corresponding category with the ``\&''
replaced by ``-''.
For example, for the category default package
\aliascon{MatrixCategory&}{MATCAT-} the abbreviation is
\spadtype{MATCAT-} since the corresponding category
\spadtype{MatrixCategory} has abbreviation \spadtype{MATCAT}.
