MATLAB Matrix-Building Functions

Some of MATLAB's convenient matrix-building functions are:

        eye       identity matrix
        zeros     matrix of zeros
        ones      matrix of ones
        diag      see below
        triu      upper triangular part of a matrix
        tril      lower triangular part of a matrix
        rand      randomly generated matrix
        hilb      Hilbert matrix
        magic     magic square
        toeplitz  see help toeplitz

For example, zeros(m,n) produces an m-by-n matrix of zeros, and zeros(n) produces an n-by-n one; if A is a matrix, then zeros(A) produces a matrix of zeros of the same size as A.

If x is a vector, diag(x) is the diagonal matrix with x down the diagonal; if A is a square matrix, then diag(A) is a vector consisting of the diagonal of A. Try to calculate the result of diag(diag(A).

Matrices can be built from blocks. For example, if A is a 3-by-3 matrix, then

     B = [A, zeros(3,2); zeros(2,3), eye(2)]

will build a certain 5-by-5 matrix. Try it.

Other Matlab Hints

Click on an item listed below to access additional MATLAB-related hints.

• A General Introduction to MATLAB
• Algorithm Efficiency Comparisons
• The Basics of MATLAB
• MATLAB Command Summary
• FOR, WHILE, and IF Loops
• Formatting Your MATLAB Output
• Generating MATLAB Graphics
• Matrix-Building Functions
• Entering Matrices in MATLAB
• Matrix Operating Functions
• Matrix Operations
• A Brief Explanation of M-Files
• Managing M-Files
• Printing a Hardcopy of Your MATLAB Session
• MATLAB Scalar Functions
• MATLAB Statements, Expressions and Variables
• Submatrices and Colon Notation
• Vector Functions

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