This is a Windows application for drawing graphs of mathematical functions. See screenshots below for an idea of what it can do. You do not choose from a limited set of offered functions - an expression evaluator can deal with an extremely wide range of expressions from simple polynomials, trigonometric, hyperbolic, exponential terms, differentials and integrals, and sums and products of series.

Requirements : 32 bit Windows

Since its release in April 2006 Descartes had over 4800
downloads from this site.

See Softpedia review

This package is **free**

Current release is version 1.2. New features in this release are:

File.. New and File..Save

Memo - this is some text saved with a file, giving an explanation
or notes about the idea behind the file contents. The memo is
displayed when the file loads, and can be reviewed/edited from
the menu Memo option.

Files remember the 'context' of what was saved eg polar or
parametric functions, and the appropriate dialog box is displayed
when the file opens.

Mouse right-click on the graph background offers various options,
some of which are obvious - zoom in and out, centre, and reset
graph limits to the original : +/- 5. The non-obvious options
will display a chord on a function, showing the 'rise and run',
and the slope of the chord as 'rise over run'. With appropriate
zoom in, continuous functions become locally straight, and the
chord slope becomes the function differential coefficient. The
other options enable the user to select where (what x value) the
chord is shown at, or to use the next function, if several
functions are being displayed.

Two implicit relations can be displayed. This is to enable simultaneous equations to be written in conventional form.

If a mouse wheel is available, it does zoom in and out.

Some 'example' files are supplied to show what can be
done.

The download is here

Unzip it into a suitable directory - c:/descartes or wherever you like. Then create a shortcut on your desktop to descartes.exe. Drag a copy to the Start menu if you like. Simple. Descartes does not alter the system registry, install or change any dlls, or anything else which would alter the operating system.

Click on the thumbnail for a full-size version

This shows the basic idea - plotting 3 functions

Inequalities can be shown. This is the region defined by

sin(x) >0

and

y > x

Functions can be plotted using polar co-ordinates, with any variable representing the angle. Here we are plotting

f( t ) = 4 sin ( a t )

with a = 2

This shows the chord feature. A chord is displayed together
with the slope value. Combined with zoom in, this can be used to
show ideas of limits, tangents and differentiation

A built-in function which performs numerical differentiation
is also available. Here one function is displayed ( x sin x )
together with its differential coefficient. In fact the nth
differential coefficient can be shown.

There is a command window where variables can be given values,
expressions calculated, functions defined and evaluated and so
on.

Parametrically-defined curves can be drawn, using any variable as the parameter. Here we are looking at

x = sin( 2 t )

y = cos( 3 t )

Implicitly-defined functions can be plotted. Here we are looking at a quadratic curve

ax^2 + bxy + cy^2 = 1

Values of a b and c can be altered