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Kaleidagraph

Origin is an application for Windows users who have much more money than brains. It is much more expensive than any of the Mac options that you named. However, you will be hard pressed to produce a nicer or more professional graph or to perform more in-depth analysis using Origin than using any of the less expensive options.

gnuplot is a CLI application that is used as the graphing engine of other applications. In that role it is fantastic. However, it is not 1993 anymore. You do not need to sacrifice ease-of-use for textbook-quality graphs. If you were a Mac user in 1993, you didn't need it then.

Now for your three options:
  1. KaleidaGraph—Hews to the interface paradigm pioneered by the venerable graphing application Cricket Graph. In my not so humble opinion, Cricket Graph's UI was the best UI for a graphing program. In addition to its intuitive UI, KG sports 95% of the power of the most powerful application listed here. This is my primary graphing application.
  2. DeltaGraph—During its early days, this application was targeted toward Excel users who needed to produce quality graphs for publication and presentation. There is probably no application available on any platform that can produce prettier graphs. Aesthetics aside, DeltaGraph is comparable in power to KaleidaGraph in its ability to analyze data and to produce science and engineering graphs.
  3. IgorPro—I have used this application for decades and have recommended it to others. It is an acquired taste. IgorPro relies on keyboard commands and scripts to perform its work. Its GUI generates scripts that can be edited and extended at will. The scripting language is powerful and easy to use. But, the graphs.... The graphs! IgorPro has a print engine that produces technical graphs as fine as any application anywhere. The demonstrations produce graphs that replicate the pages from technical reference books.
  4. QtiPlot—A Qt frameworks-based clone of Origin. Meh. Well, it is free.
Additional applications:

pro Fit—From Swiss developer Quantum Soft, this application features a powerful Pascal-like scripting language.

OmniGraphSketcher—From storied NeXTstep/MacOS X developer OmniGroup, this inexpensive application gives every Mac user the power to produce graphs that replicate the look and feel of graphs created by professional graphic artists.

Another vote for Kaleidagraph. I agree with what is said above: simple, clean, powerful (large datasets), and flexible.
 
Thanks for comments and suggestions.

I was trying to use IgorPro for couple hours trying to do what I would usually do ... and I must say it will require some learning. Working with a spreadsheet was a bit awkward to say the least.

Kaleidagraph was ok ... I am still not quite decided.

What really makes IgorPro so attractive for me right now are two things:
1. it's scriptable AND it has graphical interface, and
2. a single licence allows three installs on either OS (win or mac ... no linux unfortunately).

It seems that other people in our group are interested as well which would be great.

I still have couple weeks to play with it before I made final decision. I'll keep posting my observations ...

Cheers, R>

Another vote for Kaleidagraph. I agree with what is said above: simple, clean, powerful (large datasets), and flexible.
 
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