Add cubic spline interpolation header and example

[kurogane1031]

Hi, This is my first time attempting to contribute to an open source project, so my apologies for my lack of experience. What I attempting to do is to add the cubic spline interpolation modules in this project. Basically it's the same module as PythonRobotic cubicspline planner. But i think the algorithm itself is not path planning, but an interpolation polynomial, therefore I've added a new workspace called Polynomial.

On the side note, seems the algorithm relies on linspace function, so I've created one in the common.h. The unit test for the linspace is included. Also, one thing iIve notice is somehow the deg2rad function causing compile error due to multiple definition, so i added inline to it.

Please let me know anything i can help to make the code better..

[giacomo-b]

Hi, thank you so much for contributing. It's weird that deg2rad was causing problems, it really shouldn't need to be inlined. I'll have to look into that.

I am approving the CI pipeline and will review the files as soon as I have more time!

[codecov-commenter]

Codecov Report

Merging #14 (f8bcf33) into master (f5044a3) will increase coverage by 22.50%. The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           master      #14       +/-   ##
===========================================
+ Coverage   47.05%   69.56%   +22.50%     
===========================================
  Files           2        2               
  Lines          17       23        +6     
===========================================
+ Hits            8       16        +8     
+ Misses          9        7        -2     

Impacted Files	Coverage Δ
include/robotics/common.h	100.00% <100.00%> (+100.00%)	:arrow_up:

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[kurogane1031]

I forgot to mention that in my case, the multiple definition build error occurs when I'm attempting to build everything at once. It doesn't happen in standalone build.

Please let me know if I should remove the inline from the pull request. Also if I need to modify any other things from the code (other than the @codecov-commenter checks)

[giacomo-b]

The code doesn't seem to compile at the moment. Regarding the multiple definitions, can you describe the sequence of commands you run when you get the error? I can't seem to reproduce it. Thank you!

[kurogane1031]

The code doesn't seem to compile at the moment. Regarding the multiple definitions, can you describe the sequence of commands you run when you get the error? I can't seem to reproduce it. Thank you!

Sorry for late response. The multiple definition error only appear after I've added the linspace function and its test.

First I ran the following command

❯ cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -S test -B build/test

Then,

❯ cmake --build build/test
[ 20%] Building CXX object CMakeFiles/RoboticsTests.dir/source/common/linspace.cpp.o
[ 40%] Building CXX object CMakeFiles/RoboticsTests.dir/source/linear-control/linear-quadratic-regulator.cpp.o
[ 60%] Building CXX object CMakeFiles/RoboticsTests.dir/source/main.cpp.o
[ 80%] Building CXX object CMakeFiles/RoboticsTests.dir/source/robotics.cpp.o
[100%] Linking CXX executable RoboticsTests
/usr/bin/ld: CMakeFiles/RoboticsTests.dir/source/linear-control/linear-quadratic-regulator.cpp.o: in function `Robotics::deg2rad(double)':
linear-quadratic-regulator.cpp:(.text+0x0): multiple definition of `Robotics::deg2rad(double)'; CMakeFiles/RoboticsTests.dir/source/common/linspace.cpp.o:linspace.cpp:(.text+0x0): first defined here
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/RoboticsTests.dir/build.make:145: RoboticsTests] Error 1
make[1]: *** [CMakeFiles/Makefile2:155: CMakeFiles/RoboticsTests.dir/all] Error 2
make: *** [Makefile:146: all] Error 2