One piece of graphing software you've almost certainly already
got on your PC is Excel. Excel's
plotting capabilities are excellent for business and financial
applications, but therein lies its weakness for DPA readers: plotting
options are limited to business charts and line plots; and while
65536 rows of data are enough for those tasks, this can be restricting
when you’re dealing with large technical data sets.
There are lots of dedicated graphing products out there, but here
we'll look at two of the most popular ones designed primarily for
charting technical data. Origin (www.originlab.com) features over
200 graph types and supports a wide range of data formats and mathematical
and statistical functions, including non-linear curve-fitting.
SigmaPlot (www.sigmaplot.com) offers extensive curve-fitting and
transform options, plot wizards and excellent interfacing with
Word and Excel through ActiveX and OLE.
They do have limitations for design engineers. Their 3D plotting
capabilities are comparatively limited, and they don't support
FE or gridded data. Increasingly engineers are looking to animate
graphs to get a better view of a process, and these programs lack
animation options. Essentially they are designed to handle test
and measured data where curve-fitting and XY plots are important,
and they're focused more towards a scientific user base. They're
Windows-only programs, so if you use Linux, UNIX workstations or
Macintoshes, you'll need to find another graphing software package.
A program we've been hearing a lot about recently is Tecplot (www.tecplot.co.uk).
It hasn't suddenly burst onto the scene – it's been around
since 1987, and is now in version 10. It was originally developed
as a package for computational fluid dynamics and is the market
leader in that field. The developers, Tecplot Inc (formerly Amtec
Engineering), and UK distributors Adept Scientific are now marketing
it as a general-purpose plotting tool for engineering data, and
many of us have recently received shiny new brochures in the post.
Not without justification. Tecplot offers a great deal to design
engineers. It can handle the largest data sets, and produces stunning
plots and animations – take a look at the Plot Gallery at
www.tecplot.co.uk. It's available for Windows, UNIX, Linux and
Mac OS X, so you can transport your data across platforms. It provides
a very full range of XY, 2D and 3D plotting and data visualisation
capabilities for data from multiple sources: test data, data from
numerical simulations (gridded data) and analyses. Point-and-click
plotting makes formatting data intuitive, and you get full control
over every plot attribute without having to write code or manipulate
equations. There are built-in data loaders for Excel and AutoCAD
files, and for ASCII text files so you can work with data from
any application that exports to ASCII. A MATLAB data loader is
available as an add-on, or you can write import macros.
Many engineering designers use a maths-based tool as their core
project development software. Mathcad is ubiquitous
these days, while Mathematica (www.wolfram.com) and Maple (maple.adeptscience.co.uk)
are popular for more heavy-duty engineering computations. These
programs provide an integrated environment for performing and communicating
calculation-based work. They all provide excellent graphics capabilities,
but plotting is limited from an interactive point of view; so are
the number of data points some of them can handle. Maple and Mathematica
are language based so you need to write a program to plot and analyse.
Although some engineers see these as purely mathematical tools,
they do in fact offer a pretty comprehensive set of features for
progressing and documenting calculation-dependent design projects.
Mathcad particularly is positioned these days as an enterprise
calculation management environment. For many design engineers,
these programs meet most everyday plotting needs. If you need more
sophisticated plots than they can offer, consider how easy it is
to take your data into a separate graphing program.
That also applies to another maths-based tool, MATLAB (www.mathworks.com).
MATLAB has a strong position in the broad engineering market, especially
in signal processing and control systems development where its
sheer number-crunching power recommends it. MATLAB is not really
comparable to Mathcad, Mathematica or Maple: it's more an application
development environment. This, and other language- or array-based
tools like PV-WAVE (www.vni.com) or IDL (www.rsinc.com/idl/), integrates
mathematical computing and visualisation with a powerful technical
language. For some of us, that last point is a concern: do you
want to write a command-line script or program just to generate
a plot?
Dr Know's recommended download is the Tecplot trial version - download yours today.