Here are a few commands in MATLAB that you might find useful. load, save, freqz, filter, sound and plot. LOAD Retrieve variables from disk. LOAD fname retrieves the variables from the MAT-file 'fname.mat'. LOAD, by itself, loads from the file named 'matlab.mat'. LOAD xxx.yyy reads the ASCII file xxx.yyy, which must contain a rectangular array of numeric data, arranged in m lines with n values in each line. The result is an m-by-n matrix named xxx. To load an ASCII file that does not have a filename extension, use LOAD fname -ascii. Otherwise MATLAB adds the extension '.mat' and tries to load it as a MAT-file. To load a MAT-file that does NOT have a '.mat' extension, use LOAD fname.ext -mat. If fname is "stdio", LOAD reads from standard input. See also SAVE, SPCONVERT, FSCANF, FPRINTF. SAVE Save workspace variables on disk. SAVE fname saves all workspace variables to the binary "MAT-file" named fname.mat. The data may be retrieved with LOAD. Omitting the filename causes SAVE to use the default filename "matlab.mat". SAVE fname X saves only X. SAVE fname X Y Z saves X, Y, and Z. SAVE fname X Y Z -ascii uses 8-digit ASCII form instead of binary. SAVE fname X Y Z -ascii -double uses 16-digit ASCII form. SAVE fname X Y Z -ascii -double -tabs delimits with tabs. If fname is "stdio", SAVE sends the data to standard output. The binary formats used in MAT-files depend upon the size and type of each matrix. Small matrices and matrices with any noninteger entries are saved in floating point format requiring 8 bytes per real element. Large, integer matrices may be saved in compact formats requiring only 1, 2 or 4 bytes per element. See the External Interface Library for more details, including C and Fortran routines to read and write MAT-files from external programs. See also LOAD, DIARY, FWRITE, FPRINTF, IMWRITE. FREQZ Z-transform digital filter frequency response. When N is an integer, [H,W] = FREQZ(B,A,N) returns the N-point frequency vector W in radians and the N-point complex frequency response vector H of the filter B/A: -1 -nb jw B(z) b(1) + b(2)z + .... + b(nb+1)z H(e) = ---- = ---------------------------- -1 -na A(z) 1 + a(2)z + .... + a(na+1)z given numerator and denominator coefficients in vectors B and A. The frequency response is evaluated at N points equally spaced around the upper half of the unit circle. If N isn't specified, it defaults to 512. [H,W] = FREQZ(B,A,N,'whole') uses N points around the whole unit circle. H = FREQZ(B,A,W) returns the frequency response at frequencies designated in vector W, in radians (normally between 0 and pi). [H,F] = FREQZ(B,A,N,Fs) and [H,F] = FREQZ(B,A,N,'whole',Fs) given a sampling freq Fs in Hz return a frequency vector F in Hz. H = FREQZ(B,A,F,Fs) given sampling frequency Fs in Hz returns the complex frequency response at the frequencies designated in vector F, also in Hz. FREQZ(B,A,...) with no output arguments plots the magnitude and unwrapped phase of B/A in the current figure window. See also FILTER, FFT, INVFREQZ, FREQS and GRPDELAY. FILTER Digital filter. Y = FILTER(B, A, X) filters the data in vector X with the filter described by vectors A and B to create the filtered data Y. The filter is a "Direct Form II Transposed" implementation of the standard difference equation: y(n) = b(1)*x(n) + b(2)*x(n-1) + ... + b(nb+1)*x(n-nb) - a(2)*y(n-1) - ... - a(na+1)*y(n-na) [Y,Zf] = FILTER(B,A,X,Zi) gives access to initial and final conditions, Zi and Zf, of the delays. See also FILTFILT in the Signal Processing Toolbox. SOUND Convert vector into sound. SOUND(Y) sends the signal in vector Y out the speaker on SPARC, HP, SGI, PC, and Macintosh computers. The vector is autoscaled to provide maximum amplitude. The sound is played at the default sample rate. On the SPARC, the sample rate is fixed at 8192 Hz. On the Macintosh, the default sample rate is 22.255K Hz. SOUND(Y,FS), on the Macintosh, PC, and SGI, plays the sound at a sample frequency of FS Hz. Vector Y is automatically scaled so that the maximum and minimum values in Y correspond to the maximum and minimum input ranges allowed by the sound hardware. On the Macintosh and the SGI, the volume control on the Control Panel determines the final sound level. See also SAXIS, AUWRITE, AUREAD, WAVREAD, WAVWRITE. PLOT Plot vectors or matrices. PLOT(X,Y) plots vector X versus vector Y. 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 1, 2 or 3 character string made from the following characters: y yellow . point m magenta o circle c cyan x x-mark r red + plus g green - solid b blue * star w white : dotted k black -. dashdot -- dashed For example, PLOT(X,Y,'c+') plots a cyan plus at each data point. 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, and SUBPLOT.