# [Numpy-discussion] Re: comments on the Numerical Python manual

L. Busby busby at icf.llnl.gov
Thu Oct 19 14:27:48 CDT 2000

Fred -

I'm forwarding your mail on to numpy-discussion at lists.sourceforge.net,
which I believe is the proper venue to deal with your comments.  If
the current Numerical Python manual directed you to
support at icf.llnl.gov for support-related questions, that also needs to
be updated.

Thank you - Lee Busby

=======================================================================
From: Fred Yankowski <fred at ontosys.com>
To: support at icf.llnl.gov
Subject: comments on the Numerical Python manual

Greetings,

I'm learning NumPy by working through the "Numerical Python" manual
(Oct 9, 2000 version).  So far the manual has been a great
introduction to the software and I really appreciate the work of the
authors in providing it.

I have found a couple of problems in the text, as follows:

On page 4 in section 4, it seems that
>>> vector1 = array((1,2,4,5))
>>> vector1 = array((1,2,3,4,5))

On page 48 in section 8, the translation table used in the
"brightening" function acts instead to darken the image.  I found that
scaling proportional to a square-root function worked well:

table = (arange(256)**.5 * (255**.5)).astype('b')

One side note:  I'm surprised that the coordinate system used by the
NumTut.view function has X axis values increasing to the left.  Is
that standard for some graphing systems?  I've never worked with such
a system before.  Or am I misunderstanding what I'm seeing with view?
I'm basing this on inspection of view(arange(100)**2)) and
view(arange(100)**.5).

--
Fred Yankowski           fred at OntoSys.com      tel: +1.630.879.1312
Principal Consultant     www.OntoSys.com       fax: +1.630.879.1370
OntoSys, Inc             38W242 Deerpath Rd, Batavia, IL 60510, USA