5.4.3 Specialized 2D Plottings

• champ : vector field in R²

  //try champ
  x=[-1:0.1:1];y=x;u=ones(x);
  fx=x.*.u';fy=u.*.y';
  champ(x,y,fx,fy);
  xset("font",2,3);
  xtitle(['Vector field plot';'(with champ command)']);
  //with the color (and a large stacksize)
  x=[-1:0.004:1];y=x;u=ones(x);
  fx=x.*.u';fy=u.*.y';
  champ1(x,y,fx,fy);
  

  Figdirfigures/
  

    

  Figure 5.6: Vector field in the plane

  
  
  

• fchamp : for a vector field in R² defined by a function. The same plot than champ for a vector field defined for example by a scilab program.

• fplot2d : 2D plotting of a curve described by a function. This function plays the same role for plot2d than the previous for champ.

• grayplot : 2D plot of a surface using gray levels; the surface being defined by the matrix of the values for a grid.

• fgrayplot : the same than the previous for a surface defined by a function (scilab program).

  In fact these 2 functions can be replaced by a usual color plot with an appropriate colormap where the 3 RGB components are the same.

  R=[1:256]/256;RGB=[R' R' R'];
  xset('colormap',RGB);
  deff('[z]=surf(x,y)','z=-((abs(x)-1)**2+(abs(y)-1)**2)');
  fgrayplot(-1.8:0.02:1.8,-1.8:0.02:1.8,surf,"111",[-2,-2,2,2]);
  xset('font',2,3);
  xtitle(["Grayplot";"(with fgrayplot command)"]);
  //the same plot can be done with a ``unique'' given color
  R=[1:256]/256;
  G=0.1*ones(R);
  RGB=[R' G' G'];
  xset('colormap',RGB);
  fgrayplot(-1.8:0.02:1.8,-1.8:0.02:1.8,surf,"111",[-2,-2,2,2]);
  

  Figdirfigures/
  

    

  Figure 5.7: Gray plot with a gray colormap

  
  
  

• errbar : creates a plot with error bars