MATLAB Basics

MATLAB Basics

• The clear command is used to delete all current variables; to delete specific variables, use clear var1 var2.
• who and whos are used to request a list of variables in use during the current session, with whos also displaying size and type.

Symbols and Usage

• % is used to denote a non-executable line or portion of a line, and can be used for commenting.
• ; is used to suppress the display of a MATLAB line and can also be used to separate commands on one line.
• , is used to separate several MATLAB commands on one line.
• … is used to continue a MATLAB command onto the following line.

Numerical Values and Formats

• The format of numerical values in the command window is automatically set to have 4 values to follow the decimal, even if trailing zeros must be written.
• format long is used to display 16 numerical digits.
• format bank is used to display numbers in banking format.

Variables

• A variable name is a location used to store either the results of mathematical operations or to store data.
• A variable name can contain letters, numbers, and/or underscores, but must be less than 33 characters and start with a letter.
• Variable names are case sensitive and should be relevant to the value it represents.
• If no location is specified, ans is the default variable name.

Special Variables

• Certain variables (e.g. i, j, eps) should not be used as variable names.

Mathematical Operations

• MATLAB supports various mathematical operations, including trigonometric functions (e.g. tan, sin, cos) and complex values.
• When dealing with complex numbers, the format type should be left as short.

Matrix Manipulations

• Matrices can be indexed using A(:,3) to select columns and A(3,:) to select rows.
• Matrices can be manipulated using various operations, including exponentiation (A^2), element-wise exponentiation (A.^2), and matrix multiplication.
• The transpose of a matrix can be obtained using the ' operator.
• Matrices can be augmented using Aug=[A I] and D=[A;I].
• The matrix inverse can be computed using the inv function.
• The matrix determinant can be computed using the det function.

Arrays, Vectors, and Matrices

• The colon operator is used to create and manipulate arrays.
• Functions can be built and scripts can be created in the MATLAB editor.

Programming in MATLAB

• A function is a self-contained set of instructions designed to do a specific task.
• A function has its own workspace for variables, and information can be added to or removed from the workspace only through input and output variables.
• Function handles can be assigned to variables.
• Script files can be created using File, New, M-file.
• clc, clear all, and close all are used to clear the command window and reset variables.

Input-Output

• The input function is used to prompt the user for values directly from the command window.
• The disp function is used to display a value.
• The fprintf function is used to display a set of values.

Decisions

• The if structure is used for conditional statements.

MATLAB Functions

• The roots function is used to determine all the roots, both real and complex, of a polynomial equation.
• The lu function is used to generate the LU factorization of a matrix.
• The chol function is used to generate the Cholesky factorization of a matrix.