Installation: libsuitesparse-dev is not Optional, but rather required

[laukikk]

If followed the exact steps of installation for the C++ requirements, along with CMake and Eigen3, suitesparse is also a required dependency.

After installing CMake and Eigen3 and then running cmake .. as per installation guide, it gives the following error.

-- Compiling on Unix
-- Could NOT find CHOLMOD (missing: CHOLMOD_INCLUDE_DIR CHOLMOD_LIBRARIES) 
-- A library with BLAS API not found. Please specify library location.
-- A library with BLAS API not found. Please specify library location.
-- LAPACK requires BLAS.
-- Could NOT find CSPARSE (missing: CSPARSE_INCLUDE_DIR CSPARSE_LIBRARY) 
-- Building LGPL code as static library (affects license of the binary)
-- Could NOT find OpenGL (missing: OPENGL_opengl_LIBRARY OPENGL_glx_LIBRARY OPENGL_INCLUDE_DIR) 
CMake Warning at cmake_modules/FindQGLViewer.cmake:1 (FIND_PACKAGE):
  By not providing "FindQt5.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Qt5", but
  CMake did not find one.

  Could not find a package configuration file provided by "Qt5" with any of
  the following names:

    Qt5Config.cmake
    qt5-config.cmake

  Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
  to a directory containing one of the above files.  If "Qt5" provides a
  separate development package or SDK, be sure it has been installed.
Call Stack (most recent call first):
  CMakeLists.txt:148 (FIND_PACKAGE)


Qt5 not found. Install it and set Qt5_DIR accordingly
-- Could NOT find QGLVIEWER (missing: QGLVIEWER_INCLUDE_DIR QGLVIEWER_LIBRARY) 
-- Compiling with GCC
-- Found Eigen3: /usr/include/eigen3 (Required is at least version "2.91.0") 
-- Found PythonInterp: /usr/bin/python3.8 (found version "3.8.10") 
-- Found PythonLibs: /usr/lib/x86_64-linux-gnu/libpython3.8.so
-- Performing Test HAS_FLTO
-- Performing Test HAS_FLTO - Success
-- LTO enabled
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
CHOLMOD_INCLUDE_DIR
   used as include directory in directory /home/slam-project/g2opy/python
   used as include directory in directory /home/slam-project/g2opy/python
   used as include directory in directory /home/slam-project/g2opy/python
   used as include directory in directory /home/slam-project/g2opy/python
   used as include directory in directory /home/slam-project/g2opy/python
   used as include directory in directory /home/slam-project/g2opy/python
   used as include directory in directory /home/slam-project/g2opy/python

-- Configuring incomplete, errors occurred!
See also "/home/slam-project/g2opy/build/CMakeFiles/CMakeOutput.log".

Installing suitesparse with sudo apt-get install libsuitesparse-dev resolved the issue.

Ubuntu 20.04.