Re: [Gnuplot-info] area_under_plot

[Tait <gnu...@t4...>]

> Dear GNU !

Gnuplot has nothing to do with GNU or the FSF. It's an
unfortunate coincidence of naming, as both names came into
being at about the same time, as far as I can tell. The "gnu"
in gnuplot comes a compromise between llamaplot and nplot. (See
http://www.gnuplot.info/faq/faq.html#SECTION00032000000000000000)

> I tried but i could not  understand !
>  it will be easy for me if there is any example !
> and my main aim is to calculate the area under the curve !

This is done by integration. You can determine the integral yourself by
hand, and have gnuplot evaluate it. Or you might be able to get gnuplot to
evaluate it numerically with some work, like what's done in the recursion
demo: http://gnuplot.sourceforge.net/demo_4.4/bivariat.html.

However, a better tool for that sort of job is either a programming
language to do numeric computation, or a computer algebra system to
handle symbolic manipulation. A plotting program like gnuplot is neither
of those things.

Octave (which _is_ a GPL program) uses gnuplot for plotting, and might
be able to do calculations like what you've requested. I'm not that
familiar with it. Or use a tool like Mathematica (pieces of which are
available through, e.g. http://integrals.wolfram.com), Maple, Sage
(http://www.sagemath.org), or even lower-level utilities like Python or
the GNU scientific library, if you're willing to learn to use them.