SimpleExamples

Simple Examples of Plotting with Octave

These examples are for Octave older than 3.0.

• The Sombrero

This figure is created with the following octave code

  sombrero(32)
  gset nokey
  gset contour
  gset grid
  replot

• The Lorentz Strange Attractor

This figure is created with the following octave code

  function y = lorenz (x, t)
    y = [10 * (x(2) - x(1));
         x(1) * (28 - x(3));
         x(1) * x(2) - 8/3 * x(3)];
  endfunction
  x = lsode ("lorenz", [3; 15; 1], (0:0.01:25)');

  gset parametric
  gsplot x
  gset noxtics
  gset noytics
  gset noztics
  gset noborder
  gset nokey

• Magnetic Field / Force

This example shows the field lines around a bar magnet. It is rather colorful since I wasn't sure how to make them all the same color.

function magfield
	clearplot
	axis( [-1 1 -1 1] )
	hold on
	gset nokey

	N = [ 0, 0.2 ];
	S = [ 0, -0.2 ];

	gplot( [ S ; N ] );
	
	for i=1:100
	 	E = [ (2*rand-1) (2*rand-1) ];
		F = ( E - N ) / norm( E- N ) ^ 2 \
			+ ( S - E ) / norm( S - E ) ^ 2;
		F = unit(F) * 0.03;
					
		gplot( [ E-F; E+F ] );
	end
endfunction

function u = unit( V )
	u = V / norm( V );   
endfunction

SEAlternateMagFieldExample using a different plot technique (all the same color, possibly faster, but not interactively drawn).