Add Ceres Solver

[simon-wacker]

Ceres Solver is a large scale non-linear optimization library. It's documented and versioned.

It comes with its own system dependencies that are partly added as external projects with CMake and you can install the ones that are not on Debian-base Linux distributions with

sudo apt-get install libatlas-base-dev # Use ATLAS for BLAS & LAPACK
sudo apt-get install libsuitesparse-dev # SuiteSparse (optional)

I updated the getting started wiki entry accordingly.

Note that I had to patch GFlags with https://github.com/ise-bipv/Windows-CalcEngine/pull/10/files#diff-eca6055ba39d4288773ba85b17d27e756d0eb1bff21c7456fa41de77797fa674 to add it as external project. This patch may become obsolete or may need to be updated in new versions of GFlags

To-Dos:

• Add ATLAS as external project (this is difficult as it uses autotools and needs patches)
• Add SuiteSparse as external project (you may take inspiration from https://github.com/ise-bipv/Windows-CalcEngine/pull/10/files#diff-6857e85a31ef258bd57de3cd5fb1e0c31239cd93e0a16fba07dba83864bec5b6R181-R204 and https://github.com/ise-bipv/Windows-CalcEngine/pull/10/files#diff-fa8527355bf2b1218b356306a1d3cad240b9f6bdff3f67c14f73ff0ccb4b5f88)
• Make the build succeed on non-Linux operating systems

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For the final setup and understanding cmake I took inspiration and learned from

• An Introduction to Modern CMake
  ,
• Everything You Never Wanted to Know About CMake (Redux),
• https://github.com/Mizux/cmake-external,
• 13 valuable things I learned using CMake
• CMake: How to build external projects and include their targets
• Modern CMake,
• https://github.com/OpenDroneMap/ODM/blob/master/SuperBuild/cmake/External-GFlags.cmake,
• https://github.com/Kitware/fletch/blob/master/CMake/External_Ceres.cmake#LL73
• https://github.com/geospace-code/h5fortran
• https://indico.jlab.org/event/420/contributions/7961/attachments/6507/8734/CMakeSandCroundtable.slides.pdf
• https://github.com/DenizThatMenace/More-Modern-CMake

[simon-wacker]

@christoph-maurer I suppose that it works but I haven't checked it yet. To do so, we can make a dummy test in which we just include Ceres and solve some simple equation, or we can add a dummy of the new functionality in which we include Ceres and write a as of now failing test for the new functionality.

[christoph-maurer]

@simon-wacker Thank you! A dummy with a simple equation would be great.

[RDmitchell]

Is there an issue in Windows Calc Engine that this pull request is associated with? If not, one should be made.

Is this something that the LBNL Windows team wants to add to Windows Calc Engine?

[christoph-maurer]

Thanks for the reminder, @RDmitchell ! I have raised #172 . Does it solve your second question? This work is part of another research project and separate from EQWIN-P with its product data network buildingenvelopedata.org.