Grace

http://plasma-gate.weizmann.ac.il/Grace/

Grace is a WYSIWYG 2D plotting tool for the X Window System and M*tif. Grace runs on practically any version of Unix-like OS. As well, it has been successfully ported to VMS, OS/2, and Win9*/NT/2000/XP (some minor functionality may be missing, though).

Grace is a descendant of ACE/gr, also known as Xmgr.

Grace features at a glance:

WYSIWYG design
Convenient point-and-click graphical user interface
Precise control of graph features
True publication quality
Graphs refresh almost instantly
Exports high-resolution graphics to (E)PS, PDF, MIF, and SVG formats
Supports cross-platform PNM, JPEG and PNG formats
Device-independent Type1 font rastering, including anti-aliasing, ligatures and kerning
Graphing Flexibility
Unlimited number of curves on a graph
Up to 256 customizable colors
9 dashed line styles
32 fill patterns
10 built-in marker symbols; plus, any character glyph from any font can be used as a marker
Text annotations with subscripts, superscripts, mixed fonts, styles and colors and more complex typesetting
Curve Fitting
Linear and nonlinear least-squares
Arbitrarily complex user-defined fitting functions, including dynamically loadable C/Fortran/… modules
Fitting with constraints
Region restrictions
Fitting with arbitrary weight functions
Analysis Capability
FFT
Integration and differentiation
Histograms
Splines, including Akima splines
Interpolation and smoothing
Convolution, correlation, and covariation
Sorting
Unlimited data size; up to six dimensions plus an optional array of strings
Reads text data input files
Programmability
Built-in programming language
Math functions manipulate entire array
Variables, including arrays (1D)
User-definable functions via loadable modules
All aspects of plot outlook can be programmed
Controllable by external programs
Customization/Extensibility
Dynamic module loading - write your own C/Fortran/…
User-defined colors
User-supplied fonts and encodings