Department of Mathematics FAS Harvard University One Oxford Street Cambridge MA 02138 USA Tel: (617) 495-2171 Fax: (617) 495-5132
FAS Computer Services to Harvard University IT: (617) 495-7777.
 Matlab is a high level programming language which can be compared with Mathematica or Maple. In Unix, you start matlab by typing "matlab" at the command line. If you don't want to start matlab with a user interface, type ```matlab -nodesktop -nosplash ``` You quit it with "exit;". You can also put the commands into a file "script.m" and enter `````` matlab < script.m > script.out & ``` ``` A good starting point is to type "demo" within matlab. Besides programming, matlab can be used as a powerful "calculator". For example, in linear algebra, you would evalute the determinant, the inverse, characteristic polynomials or eigenvalues of a matrix: ```a = [1 2 3; 4 5 6; 2 3 7]; det(a) inv(a) poly(a) eig(a) ``` For calculus, you might want to integrate symbolically ```int(1/(1+x^2)) ``` or numerically ```quad('sin(x)-x',0,pi) ``` or differentiate ```diff('tan(x)*x') ``` You can plot functions of one variables ```` fplot('sin',[0,10]) ` ` t=0:0.1:10; y=sin(t); plot(t,y) ` ``` or two variables ```` [x,y]=meshgrid(-1:.2:1,-1:.2:1); z=exp(-x.^2+y.^2); mesh(z) ` ``` visualize data (for example matrix entries): ```a=rand(100); b=inv(a); imagesc(b); a=magic(100); imagesc(a); ``` find the roots of polynomials for example of p(x)=9x5+2x4+3x3+4x2+5x+7: ```roots([9 2 3 4 5 7]) ``` or finding the next root more general functions starting near a point ```fzero('cos(x)-x',0.5) ``` visualize graphs (like for example the Buckminster Fuller geodesic dome): ```[B,V]=bucky; gplot(B,V); ``` doing polynomial fits: ```x=(0:0.1:5)'; y=sin(x); p=polyfit(x,y,1); f=polyval(p,x); plot(x,y,'o',x,f,'-'); ``` It even has rendering capabilities: ```data = rand(12,12,12); isoval = .4; h = patch(isosurface(data,isoval),... 'FaceColor','blue',... 'EdgeColor','none',... 'AmbientStrength',.2,... 'SpecularStrength',.7,... 'DiffuseStrength',.4); isonormals(data,h) patch(isocaps(data,isoval),... 'FaceColor','interp',... 'EdgeColor','none') colordef black; colormap cool; daspect([1,1,1]); axis off; view(3); camlight right; camlight left; set(gcf,'Renderer','zbuffer'); material shiny; lighting phong; ``` These few lines have produced the graphics near the title.