### Qwt Installation for GUI

Before installing Qwt, one must install Qt and ensure that `QTDIR`, `LD_LIBRARY_PATH` and `PATH` point to the correct Qt4 version.

A Qwt version equal or higher than 6 is required. One can install it:

- via YUM:

       yum install qwt-devel

- via download from:
  `https://sourceforge.net/projects/qwt/files/qwt/6.0.0/qwt-6.0.0.zip/download`

  To install:

      > cd qwt-6.0.0
      > qmake
      > make
      > make install

  By default Qwt will be installed int /usr/local/qwt-6.0.0

Setup Environment

One has to ensure that `QWTDIR` and `LD_LIBRARY_PATH` have been updated to include Qwt install path and libraries.

If the environment is not set up, one can add the libraries to the .bashrc by adding `LD_LIBRARY_PATH`:

    export QWTDIR=/usr/local/qwt-6.0.0/
    export LD_LIBRARY_PATH=$QWTDIR/lib:$LD_LIBRARY_PATH