Licensing

ALGLIB uses dual licensing model. It can be used under GPL 2+ which suits needs of scientists, researchers, engineers. GPL allows free use and free modification of ALGLIB, but any derivative work (i.e. application using ALGLIB) must be distributed under GPL license too (copyleft requirement). It is good for those who just wants to solve some computational problem or to use ALGLIB in other GPL projects.

However, copyleft requirement is not good for commercial users. Basically, it means that you a) must distribute your program along with source code and b) can't restrict your users from copying your program, reselling copies or distributing them for free. That is where commercial license comes in. Commercial license:

• does not require you to distribute source code with your program.
• still gives you access to ALGLIB source code and allows to modify it as you want.
• has no royalties or distribution fees - you pay only once
• includes one year of free upgrades/bugfixes
• includes 90-days money back guarantee

Here is comparison of two ALGLIB editions – commercial and open source:

Download ALGLIB

Here you can download GPL-licensed version of ALGLIB. Commercial users may use GPL-licensed code as unlimited trial version. But if you want to distribute something that includes GPL-ed code, you have to either distribute it under GPL too or buy commercial license.