Qwt (GUI Components & utility for programs with technical background)

The Qwt library contains GUI Components and utility classes which are 
primarily useful for programs  with a  technical background. Beside a
2D  plot  widget  it  provides  scales,  sliders,  dials,  compasses,
thermometers,  wheels and knobs to control or display values, arrays, 
or ranges of type double.

Qwt 5 is a legacy version of Qwt, but it is still used by some
applications.

NOTE: You can install qwt5 and qwt (Qwt 6.x) simultaneously in Slackware.
qwt5.SlackBuild was written in a way that avoid any conflict with qwt
by applying a patch in the 'qwtconfig.pri' file and by removing qwt5 man
pages.