Graphics in FriCAS

The graphics commands are described in Chapter 7 of the FriCASBook. The syntax is:

    draw(f(x), x=a..b, options)
    draw(f(x,y), x=a..b, y=c..d, options)

vp1:=draw(sin(x), x=%pi/10..%pi)

Compiling function %B with type DoubleFloat -> DoubleFloat 
   Graph data being transmitted to the viewport manager...
   FriCAS2D data being transmitted to the viewport manager...

(1)

This command creates a "view port" and would normally (on linux for example) also display the graph.

The draw command works only under an X-Windows environment (unix/linux). There were attemps to create a new user interface (AxiomUI. fricasserver) that among other things will allow graphics to be viewed under other operating systems. But currently they stalled... If you're interested in graphics, please pitch in!

Although due to technical limitations of this system (no Xwindows environment on the Web server) we are not yet able to use draw here. However we description below a similar command named gnuDraw that can be used to generate similar graphics on this web site.

gnuDraw

It is possible to produce graphics similar to FriCAS using gnuplot on this web site. This uses GnuDraw? (GDRAW) library which is included in FriCAS (starting from version 1.2.4).

The following examples are taken from Chapter 7 Graphics of the FriCASBook.

Section: 7.1 Two-Dimensional Graphics

The general format for drawing a function defined by a formula f(x) is:

  gnudraw(f(x), x = a..b, "filename.dat", options)

where a..b defines the range of x, options are additional draw options and "filename.dat" will contain the gnuplot script necessary to create the graph.

gnuDraw(sin(x), x=%pi/10..%pi,"FriCASGraphics1.dat")

Compiling function %E with type DoubleFloat -> DoubleFloat

This file may be displayed on the web page using:

  !/begin{gnuplot}
  load "filename.dat"
  /end{gnuplot}

See below.

Technical Details

We can extract the graph data from the view port. For example we can display the list of data points that would be plotted in the graph.

(Note: we disable LaTeX output typesetting in order to save space.)

)set output tex off
 

)set output algebra on

g1:=getGraph(vp1,1)

   (3)  Graph with 1 point list

pointLists(g1)

   (4)
   [
     [[0.3141592653589793, 0.3090169943749474, 1.0, 3.0],
      [0.37306412761378793, 0.36447049987914965, 1.0, 3.0],
      [0.43196898986859655, 0.4186597375374281, 1.0, 3.0],
      [0.4908738521234052, 0.47139673682599764, 1.0, 3.0],
      [0.5497787143782138, 0.5224985647159488, 1.0, 3.0],
      [0.6086835766330224, 0.5717879602276122, 1.0, 3.0],
      [0.667588438887831, 0.619093949309834, 1.0, 3.0],
      [0.7264933011426397, 0.6642524379112817, 1.0, 3.0],
      [0.7853981633974483, 0.7071067811865475, 1.0, 3.0],
      [0.8443030256522569, 0.7475083268625967, 1.0, 3.0],
      [0.9032078879070655, 0.785316930880745, 1.0, 3.0],
      [0.9621127501618741, 0.8204014435255136, 1.0, 3.0],
      [1.0210176124166828, 0.8526401643540922, 1.0, 3.0],
      [1.0799224746714913, 0.8819212643483549, 1.0, 3.0],
      [1.1388273369262998, 0.9081431738250811, 1.0, 3.0],
      [1.1977321991811083, 0.9312149347588035, 1.0, 3.0],
      [1.2566370614359168, 0.9510565162951534, 1.0, 3.0],
      [1.3155419236907253, 0.9675990923602596, 1.0, 3.0],
      [1.3744467859455338, 0.9807852804032303, 1.0, 3.0],
      [1.4333516482003423, 0.9905693404435771, 1.0, 3.0],
      [1.4922565104551508, 0.9969173337331279, 1.0, 3.0],
      [1.5511613727099594, 0.9998072404820648, 1.0, 3.0],
      [1.6100662349647679, 0.999229036240723, 1.0, 3.0],
      [1.6689710972195764, 0.995184726672197, 1.0, 3.0],
      [1.7278759594743849, 0.987688340595138, 1.0, 3.0],
      [1.7867808217291934, 0.9767658813208727, 1.0, 3.0],
      [1.845685683984002, 0.9624552364536477, 1.0, 3.0],
      [1.9045905462388104, 0.9448060464668786, 1.0, 3.0],
      [1.963495408493619, 0.9238795325112875, 1.0, 3.0],
      [2.0224002707484274, 0.8997482840522223, 1.0, 3.0],
      [2.081305133003236, 0.8724960070727982, 1.0, 3.0],
      [2.1402099952580445, 0.8422172337162878, 1.0, 3.0],
      [2.199114857512853, 0.8090169943749488, 1.0, 3.0],
      [2.2580197197676615, 0.7730104533627385, 1.0, 3.0],
      [2.31692458202247, 0.7343225094356872, 1.0, 3.0],
      [2.3758294442772785, 0.6930873625456377, 1.0, 3.0],
      [2.434734306532087, 0.6494480483301858, 1.0, 3.0],
      [2.4936391687868955, 0.6035559419535738, 1.0, 3.0],
      [2.552544031041704, 0.5555702330196047, 1.0, 3.0],
      [2.6114488932965125, 0.5056573733779872, 1.0, 3.0],
      [2.670353755551321, 0.45399049973954964, 1.0, 3.0],
      [2.7292586178061295, 0.400748833103144, 1.0, 3.0],
      [2.788163480060938, 0.3461170570774962, 1.0, 3.0],
      [2.8470683423157466, 0.2902846772544658, 1.0, 3.0],
      [2.905973204570555, 0.23344536385590897, 1.0, 3.0],
      [2.9648780668253636, 0.17579627993435823, 1.0, 3.0],
      [3.023782929080172, 0.11753739745784152, 1.0, 3.0],
      [3.0826877913349806, 0.058870803651193036, 1.0, 3.0],
      [3.141592653589793, 1.2246467991473532e-16, 1.0, 3.0]]
     ]

)set output algebra off
 

)set output tex on

Using lower level functions the points in such a graph can also be constructed as follows:

First we need this domain

)expose GraphImage

   GraphImage is now explicitly exposed in frame initial

lineSegments := [[point [sin(x*%pi/10)$DoubleFloat, _
                  x*%pi/10], point [sin((x+1)*%pi/10)$DoubleFloat, _
                 (x+1)*%pi/10]] for x in 1..10]

(2)

lineColors := [light blue() for i in 1..10]

(3)

pointColors  := [dark blue() for i in 1..10]

(4)

lineSize := [6 for i in 1..10]

(5)

g2:=makeGraphImage(lineSegments, lineColors, pointColors, lineSize)

(6)

)set output tex off
 

)set output algebra on

pointLists(g2)

   (10)
   [
     [[0.3090169943749474, 0.3141592653589793],
      [0.5877852522924731, 0.6283185307179586]]
     ,

     [[0.5877852522924731, 0.6283185307179586],
      [0.8090169943749475, 0.9424777960769379]]
     ,

     [[0.8090169943749475, 0.9424777960769379],
      [0.9510565162951535, 1.2566370614359172]]
     ,
    [[0.9510565162951535, 1.2566370614359172], [1.0, 1.5707963267948966]],
    [[1.0, 1.5707963267948966], [0.9510565162951536, 1.8849555921538759]],

     [[0.9510565162951536, 1.8849555921538759],
      [0.8090169943749475, 2.199114857512855]]
     ,

     [[0.8090169943749475, 2.199114857512855],
      [0.5877852522924732, 2.5132741228718345]]
     ,

     [[0.5877852522924732, 2.5132741228718345],
      [0.3090169943749475, 2.827433388230814]]
     ,

     [[0.3090169943749475, 2.827433388230814],
      [1.2246467991473532e-16, 3.141592653589793]]
     ,

     [[1.2246467991473532e-16, 3.141592653589793],
      [- 0.3090169943749469, 3.455751918948772]]
     ]

)set output algebra off
 

)set output tex on