Matlab provides excellent online help. Just try to be a little creative and you can find help on almost anything Matlab can do.

Type help to find a list of Matlab help topics

>> help HELP topics: eyre/matlab - Eyre functions - generally for differential equations matlab/general - General purpose commands. matlab/ops - Operators and special characters. matlab/lang - Programming language constructs. matlab/elmat - Elementary matrices and matrix manipulation. matlab/elfun - Elementary math functions. matlab/specfun - Specialized math functions. matlab/matfun - Matrix functions - numerical linear algebra. matlab/datafun - Data analysis and Fourier transforms. matlab/polyfun - Interpolation and polynomials. matlab/funfun - Function functions and ODE solvers. matlab/sparfun - Sparse matrices. matlab/graph2d - Two dimensional graphs. matlab/graph3d - Three dimensional graphs. matlab/specgraph - Specialized graphs. matlab/graphics - Handle Graphics. matlab/uitools - Graphical user interface tools. matlab/strfun - Character strings. matlab/iofun - File input/output. matlab/timefun - Time and dates. matlab/datatypes - Data types and structures. matlab/demos - Examples and demonstrations. simulink/simulink - Simulink simulink/blocks - Simulink block library. simulink/simdemos - Simulink demonstrations and samples. simulink/dee - Differential Equation Editor toolbox/compiler - MATLAB Compiler toolbox/control - Control System Toolbox. control/obsolete - (No table of contents file) toolbox/ident - System Identification Toolbox. images/images - Image Processing Toolbox. images/imdemos - Image Processing Toolbox --- demos and sample images toolbox/local - Preferences. toolbox/optim - Optimization Toolbox. toolbox/signal - Signal Processing Toolbox. stateflow/stateflow - Stateflow stateflow/sfdemos - (No table of contents file) toolbox/symbolic - Symbolic Math Toolbox. toolbox/tour - MATLAB Tour For more help on directory/topic, type "help topic".

To see the graphics subsection, type

>> help graph2d Two dimensional graphs. Elementary X-Y graphs. plot - Linear plot. loglog - Log-log scale plot. semilogx - Semi-log scale plot. semilogy - Semi-log scale plot. polar - Polar coordinate plot. plotyy - Graphs with y tick labels on the left and right. Axis control. axis - Control axis scaling and appearance. zoom - Zoom in and out on a 2-D plot. grid - Grid lines. box - Axis box. hold - Hold current graph. axes - Create axes in arbitrary positions. subplot - Create axes in tiled positions. daspect - Data aspect ratio. pbaspect - Plot box aspect ratio. xlim - X limits. ylim - Y limits. Graph annotation. legend - Graph legend. title - Graph title. xlabel - X-axis label. ylabel - Y-axis label. text - Text annotation. gtext - Place text with mouse. plotedit - Experimental graph editing and annotation tools. Hardcopy and printing. print - Print graph or SIMULINK system; or save graph to M-file. printopt - Printer defaults. orient - Set paper orientation. See also GRAPH3D, SPECGRAPH.

To see the help for a standard plot of (x,y) data

>> help plot PLOT Linear plot. PLOT(X,Y) plots vector Y versus vector X. If X or Y is a matrix, then the vector is plotted versus the rows or columns of the matrix, whichever line up. PLOT(Y) plots the columns of Y versus their index. If Y is complex, PLOT(Y) is equivalent to PLOT(real(Y),imag(Y)). In all other uses of PLOT, the imaginary part is ignored. Various line types, plot symbols and colors may be obtained with PLOT(X,Y,S) where S is a character string made from one element from any or all the following 3 colunms: y yellow . point - solid m magenta o circle : dotted c cyan x x-mark -. dashdot r red + plus -- dashed g green * star b blue s square w white d diamond k black v triangle (down) ^ triangle (up) < triangle (left) > triangle (right) p pentagram h hexagram For example, PLOT(X,Y,'c+:') plots a cyan dotted line with a plus at each data point; PLOT(X,Y,'bd') plots blue diamond at each data point but does not draw any line. PLOT(X1,Y1,S1,X2,Y2,S2,X3,Y3,S3,...) combines the plots defined by the (X,Y,S) triples, where the X's and Y's are vectors or matrices and the S's are strings. For example, PLOT(X,Y,'y-',X,Y,'go') plots the data twice, with a solid yellow line interpolating green circles at the data points. The PLOT command, if no color is specified, makes automatic use of the colors specified by the axes ColorOrder property. The default ColorOrder is listed in the table above for color systems where the default is yellow for one line, and for multiple lines, to cycle through the first six colors in the table. For monochrome systems, PLOT cycles over the axes LineStyleOrder property. PLOT returns a column vector of handles to LINE objects, one handle per line. The X,Y pairs, or X,Y,S triples, can be followed by parameter/value pairs to specify additional properties of the lines. See also SEMILOGX, SEMILOGY, LOGLOG, GRID, CLF, CLC, TITLE, XLABEL, YLABEL, AXIS, AXES, HOLD, COLORDEF, and SUBPLOT.

The first paragraph states that to see a plot of (x,y) data pairs, type plot(x,y) where x and y are vectors of data. Cut and paste the following into your Matlab window.

>> x = 1:4 >> y = rand(4,1) >> plot(x,y)

For window based help, from the Matlab prompt type helpwin. This accesses the same help data that you have just been working with.

PLOT(X,Y) plots vector Y versus vector X.

>> plot(x,y)

From the Matlab prompt, type

>>helpdeskThis access the Matlab help page that is part of the installed version of Matlab.

Help and software are available at the Matlab home page

Finally, there is a newsgroup on Usenet, comp.soft-sys.matlab, that is devoted to Matlab. Reading and participating in the group is a good way to improve your Matlab skills.

These Matlab commands are extremely useful to determine the available Matlab variables, and to clear those variables. Type help who, or better yet type

>> who >> whos >> clear >> who

The Matlab commands you issue and the results you obtain can be saved to a disk file containing ascii data. To save the data type

>> diary fooThis records your Matlab session in a disk file named