R-alpha: New version of R for testing

[Ross Ihaka]

The newest version of R for Unix (version 0.50 alpha-1) is now (or will
soon be) available from the following sites.

    NORTH AMERICA:
	http://lib.stat.cmu.edu/R/Alpha

    EUROPE:
        ftp://ftp.stat.math.ethz.ch/R/
        ftp://statlab.uni-heidelberg.de/pub/mirrors/auckland/R/

    JAPAN:
        ftp://ftp.u-aizu.ac.jp/pub/lang/R/

    NEW ZEALAND:
        ftp://stat.auckland.ac.nz/pub/R/

Please obtain a copy from site close to you.  Note that New Zealand
is not close to anywhere other than itself :-).

This is primarily a bug-fix release, although there is some new
functionalty.  As noted in the 0.49 release announcement, the primary
goal at present is stability.  This is partly for the benefit of anyone
who might be using R, but also so that we we can bring the PC and
Mac versions into sync with the Unix version.

The "alpha-1" indicates that there may be a few stability problems with
this version.  This is because there are been a number of very low-level
changes which have not been exercised as much as they might.  We hope
that these can be found and fixed in a couple of patch cycles.  Then
we will declare it to be "R-0.50 stable".

This version owes a good deal to Martin Maechler who probably did as
much bug-fixing as R+R together this time.

	R + R + M


We have not kept good a records of bug fixes or updates the TASKS list
(we should have this updated for the "stable" release).  A partial list
of changes follows.

-------------------------------------------------------------------

		  CHANGES IN VERSION R VERSION 0.50

WARNING!!!

 o  A change in the way that "expressions" are implemented means that
    saved data images which contain expressions will probably not
    restore properly.

NEW FEATURES

 o  "expressions" are now implemented as a basic type rather than as
    a class of object.  This change was made as move toward compatibility
    with S and also to implement mathematical annotation in graphs.

 o  "eigen" can now handle complex and non-symmetric matrices.

 o  Libraries are now attached by loading their code into newly created
    environment frames on the search path rather than in with the general
    system code.  This means that libraries can be unloaded as well as
    loaded.  They can also have .First.lib and .Last.lib functions.

 o  There is now an experimental function called "delay" which creates
    a promise to evaluate an expression.  This provides direct access
    to the lazy evaluation mechanism used by R.

 o  >>>>  'make tests'   allows to test--run all the help() examples.
 
 o  New functions   matplot / matpoints / matlines.

 o  cut has 2 new arguments. 'right = TRUE' gives intervals closed on the
	right, open to the left (as S); 'right = FALSE' allows to reverse
	this. The code for default label construction has been enhanced,
	and can be controlled by the new argument 'dig.lab'.

 o  legend(.) has 2 new arguments 'cex' (obvious) and 'merge = FALSE'.
	-> ?legend.

 o  deparse  has a 2nd argument allowing for a kind of line width.

 o  many help(.) pages have been updated with working examples,
	and several new ones have been created.

BUG FIXES

 o  A bug which prevented the "pictex" graphics driver from working
    has been fixed.

 o  Regression diagnostics obtained with "lm.influence" now work when
    there are weights.	This means they should work for glms.

 o  There was a problem in parsing files from statements which were
    separated from following statements by ";" (e.g. data(iris); iris).
    This is fixed.

 o  Comments are handled better in functions.  The rule is that they
    are shifted to just before their statements.  Comments after the
    last statement of a function are lost.

 o  It is now possible to perform complicated mutations of expressions.
    For example
	e <- quote(f(x=1,y=2))
	names(e)[[2]] <- "a"
    will change the x= argument tag into a=.  In the past this produced
    odd error messages.

 o  The length function now tries to return a "sensible" value for all
    the built-in types.	 For example, symbols now have length 1.

 o  "update" should now work in both "lm" and "glm" models.

 o  The functions Re, Im, Mod, Arg and Conj will now accept real-valued
    arguments and return the obvious results.

 o  Minor graphics cleanup.

 o  A fix for convergence problems in glm from Thomas Lumley included.

 o  A new version of qt() should not take infinitely long to get an
    answer in the large degrees if freedom case.  The underlying code
    (Hill 1970, CACM) appears to be much faster and more accurate than
    Splus.

 o  A final Newton step has beed added to give a final "polish" to
    the quantiles produced by pnorm().	These should be close to full
    accuracy now.

 o  A bug in qbeta found by Martin Maechler has been fixed.  This should
    speed up quantile computation for the F and Beta distributions.

 o  rainbow(.) now allows "start > end" indexing the "color circle".
    topo.colors(n), terrain.colors(n), heat.colors(n) now also work for n=1,2.

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