MADlib builds Eigen using the EIGEN_MPL2_ONLY flag enabled.

From the Eigen Licensing page
(http://eigen.tuxfamily.org/index.php?title=Main_Page)

Eigen is Free Software. Starting from the 3.1.1 version, it is licensed 
under the MPL2, which is a simple weak copyleft license.  Common 
questions about the MPL2 are answered in the official MPL2 FAQ 
(http://www.mozilla.org/MPL/2.0/FAQ.html).

Note that currently, a few features rely on third-party code licensed 
under the LGPL: SimplicialCholesky, AMD ordering, and constrained_cg. 
Such features can be explicitly disabled by compiling with the 
EIGEN_MPL2_ONLY preprocessor symbol defined.   

Virtually any software may use Eigen. For example, closed-source 
software may use Eigen without having to disclose its own source code. 
Many proprietary and closed-source software projects are using Eigen 
right now, as well as many BSD-licensed projects.

------

Mozilla Public License
Version 2.0

1. Definitions

1.1. “Contributor”
means each individual or legal entity that creates, contributes to the 
creation of, or owns Covered Software.

1.2. “Contributor Version”
means the combination of the Contributions of others (if any) used by 
a Contributor and that particular Contributor’s Contribution.

1.3. “Contribution”
means Covered Software of a particular Contributor.

1.4. “Covered Software”
means Source Code Form to which the initial Contributor has attached 
the notice in Exhibit A, the Executable Form of such Source Code Form, 
and Modifications of such Source Code Form, in each case including 
portions thereof.

1.5. “Incompatible With Secondary Licenses”
means

• that the initial Contributor has attached the notice described in 
Exhibit B to the Covered Software; or

• that the Covered Software was made available under the terms of 
version 1.1 or earlier of the License, but not also under the terms of 
a Secondary License.

1.6. “Executable Form”
means any form of the work other than Source Code Form.

1.7. “Larger Work”
means a work that combines Covered Software with other material, in a 
separate file or files, that is not Covered Software.

1.8. “License”
means this document.

1.9. “Licensable”
means having the right to grant, to the maximum extent possible, 
whether at the time of the initial grant or subsequently, any and all 
of the rights conveyed by this License.

1.10. “Modifications”
means any of the following:

• any file in Source Code Form that results from an addition to, 
deletion from, or modification of the contents of Covered Software; or

• any new file in Source Code Form that contains any Covered Software.

1.11. “Patent Claims” of a Contributor
means any patent claim(s), including without limitation, method, 
process, and apparatus claims, in any patent Licensable by such 
Contributor that would be infringed, but for the grant of the License, 
by the making, using, selling, offering for sale, having made, import, 
or transfer of either its Contributions or its Contributor Version.

1.12. “Secondary License”
means either the GNU General Public License, Version 2.0, the GNU 
Lesser General Public License, Version 2.1, the GNU Affero General 
Public License, Version 3.0, or any later versions of those licenses.

1.13. “Source Code Form”
means the form of the work preferred for making modifications.

1.14. “You” (or “Your”)
means an individual or a legal entity exercising rights under this 
License. For legal entities, “You” includes any entity that 
controls, is controlled by, or is under common control with You. For  
purposes of this definition, “control” means (a) the power, direct or 
indirect, to cause the direction or management of such entity, whether 
by contract or otherwise, or (b) ownership of more than fifty percent 
(50%) of the outstanding shares or beneficial ownership of such entity.

2. License Grants and Conditions

2.1. Grants

Each Contributor hereby grants You a world-wide, royalty-free, 
non-exclusive license:

• under intellectual property rights (other than patent or trademark) 
Licensable by such Contributor to use, reproduce, make available, 
modify, display, perform, distribute, and otherwise exploit its 
Contributions, either on an unmodified basis, with Modifications, or as 
part of a Larger Work; and

• under Patent Claims of such Contributor to make, use, sell, offer 
for sale, have made, import, and otherwise transfer either its 
Contributions or its Contributor Version.

2.2. Effective Date

The licenses granted in Section 2.1 with respect to any Contribution 
become effective for each Contribution on the date the Contributor 
first distributes such Contribution.

2.3. Limitations on Grant Scope

The licenses granted in this Section 2 are the only rights granted 
under this License. No additional rights or licenses will be implied 
from the distribution or licensing of Covered Software under this 
License. Notwithstanding Section 2.1(b) above, no patent license is 
granted by a Contributor:

• for any code that a Contributor has removed from Covered Software; 
or

• for infringements caused by: (i) Your and any other third party’s 
modifications of Covered Software, or (ii) the combination of its 
Contributions with other software (except as part of its Contributor 
Version); or

• under Patent Claims infringed by Covered Software in the absence of 
its Contributions.

This License does not grant any rights in the trademarks, service 
marks, or logos of any Contributor (except as may be necessary to 
comply with the notice requirements in Section 3.4).

2.4. Subsequent Licenses

No Contributor makes additional grants as a result of Your choice to 
distribute the Covered Software under a subsequent version of this 
License (see Section 10.2) or under the terms of a Secondary License 
(if permitted under the terms of Section 3.3).

2.5. Representation

Each Contributor represents that the Contributor believes its 
Contributions are its original creation(s) or it has sufficient rights 
to grant the rights to its Contributions conveyed by this License.

2.6. Fair Use

This License is not intended to limit any rights You have under 
applicable copyright doctrines of fair use, fair dealing, or other 
equivalents.

2.7. Conditions

Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted 
in Section 2.1.

3. Responsibilities

3.1. Distribution of Source Form

All distribution of Covered Software in Source Code Form, including any 
Modifications that You create or to which You contribute, must be under 
the terms of this License. You must inform recipients that the Source 
Code Form of the Covered Software is governed by the terms of this 
License, and how they can obtain a copy of this License. You may not 
attempt to alter or restrict the recipients’ rights in the Source Code 
Form.

3.2. Distribution of Executable Form

If You distribute Covered Software in Executable Form then:

• such Covered Software must also be made available in Source Code 
Form, as described in Section 3.1, and You must inform recipients of 
the Executable Form how they can obtain a copy of such Source Code Form 
by reasonable means in a timely manner, at a charge no more than the 
cost of distribution to the recipient; and

• You may distribute such Executable Form under the terms of this 
License, or sublicense it under different terms, provided that the 
license for the Executable Form does not attempt to limit or alter the 
recipients’ rights in the Source Code Form under this License.

3.3. Distribution of a Larger Work

You may create and distribute a Larger Work under terms of Your choice, 
provided that You also comply with the requirements of this License for 
the Covered Software. If the Larger Work is a combination of Covered 
Software with a work governed by one or more Secondary Licenses, and 
the Covered Software is not Incompatible With Secondary Licenses, this 
License permits You to additionally distribute such Covered Software 
under the terms of such Secondary License(s), so that the recipient of 
the Larger Work may, at their option, further distribute the Covered 
Software under the terms of either this License or such Secondary 
License(s).

3.4. Notices

You may not remove or alter the substance of any license notices 
(including copyright notices, patent notices, disclaimers of warranty, 
or limitations of liability) contained within the Source Code Form of 
the Covered Software, except that You may alter any license notices to 
the extent required to remedy known factual inaccuracies.

3.5. Application of Additional Terms

You may choose to offer, and to charge a fee for, warranty, support, 
indemnity or liability obligations to one or more recipients of Covered 
Software. However, You may do so only on Your own behalf, and not on 
behalf of any Contributor. You must make it absolutely clear that any 
such warranty, support, indemnity, or liability obligation is offered 
by You alone, and You hereby agree to indemnify every Contributor for 
any liability incurred by such Contributor as a result of warranty, 
support, indemnity or liability terms You offer. You may include 
additional disclaimers of warranty and limitations of liability 
specific to any jurisdiction.

4. Inability to Comply Due to Statute or Regulation

If it is impossible for You to comply with any of the terms of this 
License with respect to some or all of the Covered Software due to 
statute, judicial order, or regulation then You must: (a) comply with  
the terms of this License to the maximum extent possible; and (b) 
describe the limitations and the code they affect. Such description 
must be placed in a text file included with all distributions of the 
Covered Software under this License. Except to the extent prohibited 
by statute or regulation, such description must be sufficiently 
detailed for a recipient of ordinary skill to be able to understand it.

5. Termination

5.1. The rights granted under this License will terminate automatically 
if You fail to comply with any of its terms. However, if You become 
compliant, then the rights granted under this License from a  
particular Contributor are reinstated (a) provisionally, unless and 
until such Contributor explicitly and finally terminates Your grants, 
and (b) on an ongoing basis, if such Contributor fails to notify You 
of the non-compliance by some reasonable means prior to 60 days after 
You have come back into compliance. Moreover, Your grants from a 
particular Contributor are reinstated on an ongoing basis if such 
Contributor notifies You of the non-compliance by some reasonable 
means, this is the first time You have received notice of 
non-compliance with this License from such Contributor, and You become 
compliant prior to 30 days after Your receipt of the notice.

5.2. If You initiate litigation against any entity by asserting a 
patent infringement claim (excluding declaratory judgment actions, 
counter-claims, and cross-claims) alleging that a Contributor Version 
directly or indirectly infringes any patent, then the rights granted to 
You by any and all Contributors for the Covered Software under Section 
2.1 of this License shall terminate.

5.3. In the event of termination under Sections 5.1 or 5.2 above, all 
end user license agreements (excluding distributors and resellers)
which have been validly granted by You or Your distributors under this 
License prior to termination shall survive termination.

6. Disclaimer of Warranty

Covered Software is provided under this License on an “as is” 
basis, without warranty of any kind, either expressed, implied, or 
statutory, including, without limitation, warranties that the Covered 
Software is free of defects, merchantable, fit for a particular purpose 
or non-infringing. The entire risk as to the quality and performance of 
the Covered Software is with You. Should any Covered Software prove 
defective in any respect, You (not any Contributor) assume the cost of 
any necessary servicing, repair, or correction. This disclaimer of 
warranty constitutes an essential part of this License. No use of any 
Covered Software is authorized under this License except under this 
disclaimer.

7. Limitation of Liability

Under no circumstances and under no legal theory, whether tort 
(including negligence), contract, or otherwise, shall any Contributor, 
or anyone who distributes Covered Software as permitted above, be 
liable to You for any direct, indirect, special, incidental, or 
consequential damages of any character including, without limitation, 
damages for lost profits, loss of goodwill, work stoppage, computer 
failure or malfunction, or any and all other commercial damages or 
losses, even if such party shall have been informed of the possibility 
of such damages. This limitation of liability shall not apply to 
liability for death or personal injury resulting from such party’s 
negligence to the extent applicable law prohibits such limitation. Some 
jurisdictions do not allow the exclusion or limitation of incidental or 
consequential damages, so this exclusion and limitation may not apply 
to You.

8. Litigation

Any litigation relating to this License may be brought only in the 
courts of a jurisdiction where the defendant maintains its principal 
place of business and such litigation shall be governed by laws of that 
jurisdiction, without reference to its conflict-of-law provisions. 
Nothing in this Section shall prevent a party’s ability to bring 
cross-claims or counter-claims.

9. Miscellaneous

This License represents the complete agreement concerning the subject 
matter hereof. If any provision of this License is held to be 
unenforceable, such provision shall be reformed only to the extent  
necessary to make it enforceable. Any law or regulation which provides 
that the language of a contract shall be construed against the drafter 
shall not be used to construe this License against a Contributor.

10. Versions of the License

10.1. New Versions

Mozilla Foundation is the license steward. Except as provided in 
Section 10.3, no one other than the license steward has the right to 
modify or publish new versions of this License. Each version will be 
given a distinguishing version number.

10.2. Effect of New Versions

You may distribute the Covered Software under the terms of the version 
of the License under which You originally received the Covered 
Software, or under the terms of any subsequent version published by the 
license steward.

10.3. Modified Versions

If you create software not governed by this License, and you want to 
create a new license for such software, you may create and use a 
modified version of this License if you rename the license and remove 
any references to the name of the license steward (except to note that 
such modified license differs from this License).

10.4. Distributing Source Code Form that is Incompatible With Secondary 
Licenses

If You choose to distribute Source Code Form that is Incompatible With 
Secondary Licenses under the terms of this version of the License, the 
notice described in Exhibit B of this License must be attached.

Exhibit A - Source Code Form License Notice

This Source Code Form is subject to the terms of the Mozilla Public 
License, v. 2.0. If a copy of the MPL was not distributed with this 
file, You can obtain one at http://mozilla.org/MPL/2.0/.

If it is not possible or desirable to put the notice in a particular 
file, then You may include the notice in a location (such as a LICENSE 
file in a relevant directory) where a recipient would be likely to look 
for such a notice.

You may add additional accurate notices of copyright ownership.

Exhibit B - “Incompatible With Secondary Licenses” Notice

This Source Code Form is “Incompatible With Secondary Licenses”, as 
defined by the Mozilla Public License, v. 2.0.