On line help is available for many of the functions in XLISP-STAT
.
As an example, here is how you would get help
for the function ` median`:

> (help 'median) MEDIAN [function-doc] Args: (x) Returns the median of the elements of X. NIL >Note the quote in front of

If you are not sure about the name of a function you may still be able to get some help. Suppose you want to find out about functions related to the normal distribution. Most such functions will have ``norm'' as part of their name. The expression

(help* 'norm)will print the help information for all symbols whose names contain the string ``norm'':

> (help* 'norm) ------------------------------------------------------------------------------ Sorry, no help available on NORM ------------------------------------------------------------------------------ Sorry, no help available on NORM-2 ------------------------------------------------------------------------------ Sorry, no help available on NORMAL ------------------------------------------------------------------------------ NORMAL-CDF [function-doc] Args: (x) Returns the value of the standard normal distribution function at X. Vectorized. ------------------------------------------------------------------------------ NORMAL-DENS [function-doc] Args: (x) Returns the density at X of the standard normal distribution. Vectorized. ------------------------------------------------------------------------------ NORMAL-QUANT [function-doc] Args (p) Returns the P-th quantile of the standard normal distribution. Vectorized. ------------------------------------------------------------------------------ NORMAL-RAND [function-doc] Args: (n) Returns a list of N standard normal random numbers. Vectorized. ------------------------------------------------------------------------------ NIL >The symbols

The first time a help function is used will take some time -- the help file is scanned and the positions of all entries in the file are recorded. Subsequent calls will be faster.

Let me briefly explain the notation used in the information printed by
` help` to describe the arguments a function expects
. Most functions expect a fixed
set of arguments, described in the help message by a line like

Args: (x y z)Some functions can take one or more optional arguments. The arguments for such a function might be listed as

Args: (x &optional y (z t))This means that

Another form of optional argument is the * keyword argument*. The
histogram function for example takes arguments

Args: (data &key (title "Histogram"))The

(histogram purchases :title "Purchases")Thus to give a value for a keyword argument you give the keyword for the argument, a symbol consisting of a colon followed by the argument name, and then the value for the argument. If a function can take several keyword arguments then these may be specified in any order, following the required and optional arguments.

Finally, some functions can take an arbitrary number of arguments. This is denoted by a line like

Args: (x &rest args)The argument

In addition to providing information about functions ` help` also
gives information about data types and certain variables. For example,

> (help 'complex) COMPLEX [function-doc] Args: (realpart &optional (imagpart 0)) Returns a complex number with the given real and imaginary parts. COMPLEX [type-doc] A complex number NIL >shows the function and type documentation for

> (help 'pi) PI [variable-doc] The floating-point number that is approximately equal to the ratio of the circumference of a circle to its diameter. NIL >shows the variable documentation for

Tue Jan 21 15:04:48 CST 1997