Avogadro

Avogadro is an advanced molecular editor designed for cross-platform use in computational chemistry, molecular modeling, bioinformatics, materials science, and related areas. It offers flexible rendering and a powerful plugin architecture.


Cross-Platform: Molecular builder/editor for Windows, Linux, and Mac OS X.
Free, Open Source: Easy to install and all source code is available under the GNU GPL.
International: Translations into French and German, with more languages to come.
Intuitive: Built to work easily for students and advanced researchers both.
Fast: Supports multi-threaded rendering and computation.
Extensible: Plugin architecture for developers, including rendering, interactive tools, commands, and Python scripts.
Flexible: Features include Open Babel import of files, input generation for multiple computational chemistry packages, crystallography, and biomolecules. Find out more.

SpeQ - Small and free mathematics software

' SpeQ is a small mathematics program with a simple, intuitive
' interface. How to use SpeQ? Just enter a calculation

通过简单地输入公式或者通过列表查找函数，完成数学计算和函数绘图。非常小（100k左右）。

FreeCAD

免费的CAD软件，类似于3D MAX或者 AutoCAD
相关介绍http://juergen-riegel.net/FreeCAD/Docu/index.php?title=Main_Page
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FreeCAD will be a general purpose 3D CAD modeller. The development will be completely Open Source. As modern 3D CAX modellers it will have a 2D component to extract design drawings from the 3D model, but 2D (like AutoCAD) is not the focus, neither are animation and organic shapes (Maya, 3D StudioMAX, Cinema 4D). FreeCAD will aim directly to mechanical engineering, product design and related features (like CatiaV4 and V5, and SolidWorks). It will be a feature based parametric modeler.

SciGraphica - Linux 下的科学图像处理

SciGraphica没有Windows版本，所以这可能影响了它的普及。我也没有用过，不过似乎和Origin一样强大。

http://scigraphica.sourceforge.net/index.html
windows下的同类型免费软件可以参考Gnuplot,或者Scilab 这样附带绘图功能的科学计算程序

SciGraphica is a scientific application for data analysis and technical graphics. It pretends to be a clone of the popular commercial (and expensive) application "Microcal Origin". It fully supplies plotting features for 2D, 3D and polar charts. The aim is to obtain a fully-featured, cross-plattform, user-friendly, self-growing scientific application. It is free and open-source, released under the GPL license.

Main features:

• You can plot functions and manipulate data in worksheets.
• You can open several worksheets and plots and work with them interactively and at the same time.
  
• The plots are fully configurable using a control panel dialog.
  
• The look and feel is completely WYSIWYG.
  
• Production/Publication quality PostScript output.
  
• You can interact with the plots double-clicking, dragging and moving objects with the mouse.
  
• Native XML file format.
  
• You can insert Python expressions in the worksheets.
  
• Terminal with command-line Python interface for interacting with plots and worksheets
  

It is completely programmed in C from scratch, using the GTK+ and GtkExtra libraries, and released under the GPL agreement.

SciGraphica - Linux 下的科学图像处理

SciGraphica没有Windows版本，所以这可能影响了它的普及。我也没有用过，不过似乎和Origin一样强大。

http://scigraphica.sourceforge.net/index.html
windows下的同类型免费软件可以参考Gnuplot,或者Scilab 这样附带绘图功能的科学计算程序

SciGraphica is a scientific application for data analysis and technical graphics. It pretends to be a clone of the popular commercial (and expensive) application "Microcal Origin". It fully supplies plotting features for 2D, 3D and polar charts. The aim is to obtain a fully-featured, cross-plattform, user-friendly, self-growing scientific application. It is free and open-source, released under the GPL license.

Main features:

• You can plot functions and manipulate data in worksheets.
• You can open several worksheets and plots and work with them interactively and at the same time.
  
• The plots are fully configurable using a control panel dialog.
  
• The look and feel is completely WYSIWYG.
  
• Production/Publication quality PostScript output.
  
• You can interact with the plots double-clicking, dragging and moving objects with the mouse.
  
• Native XML file format.
  
• You can insert Python expressions in the worksheets.
  
• Terminal with command-line Python interface for interacting with plots and worksheets
  

It is completely programmed in C from scratch, using the GTK+ and GtkExtra libraries, and released under the GPL agreement.

Scilab - 科学计算软件，Matlab替代品

开源世界以前就有至少一个以替代Matlab为目标的软件，这个软件是octave，现在仍然是很多版本Linux的默认软件包，但是它的开发似乎不是怎么活跃。但是Scilab出现了，可以说完全动摇了octave的地位。
Scilab有专门的实验室为其开发支持，同时每年有workshop和奖项，这些都为开发增添了生机。中国的开发人员也做了不少的贡献。
http://www.scilab.org/
中文网站地址

中文网站上的介绍如下：
“
最为基本的、通用的科学计算软件应该走向自由和共享。只有这样才能最大限度地提高计算机应用的普及程度，共享的结果可以汇集更广泛的资料，使软件不断趋于尽善尽美的水平。科学计算自由软件SCILAB正是在追求“自由，同创，共享”这样一种理念下应运而生的，并成为自由软件的一面旗帜。

科学计算（如加、减、乘、除、微积分、逻辑推理等）是计算机应用的主要内容之一。以完成这一类科学计算问题为目的应用软件，我们称之为科学计算软件。在此，我们应该对“科学计算软件”一词有更广义的理解。它不仅限于科学方面的应用，也包括各种工程技术、金融、经济等方面的应用。目前这类软件多数是以数值计算形式为主，然而基于符号推导（如公式推导）的计算软件也变得日益普及。除此之外，科学计算可视化同样是该类软件的涵盖内容。
”

Microsoft Powertoy Calc 功能更强的小计算器

微软的Windows视窗操作系统自带了一个模拟普通电子计算器的小计算器程序，为calc.exe，
而在他们的PowerToy中，也提供了一个免费的但是具有画图功能和自定义函数等功能的计算器。

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所有的PowerToys