3 Getting Help from Within MATLAB If you know the name of a function which you would like to learn how to use, use the help command > help functionname This command displays a description of the function and generally also includes a list of related functions. If you cannot remember the name of the function, use the lookfor' command and the name of some keyword associated with the function > lookfor keyword This command will display a list of functions that include the keyword in their descriptions Other help commands that you may find useful are ' info, what, andwhich. descrip- tions of these commands can be found by using the help command. MATLAB also contains a variety of demos that can be with the 'demo'command 4 MATLAB Variables- Scalars. Vectors, and matri ces MATLAB Stores variables in the form of matrices which are mxn where m is the number of rows and n the number of columns. a 1 x1 matrix is a scalar: a 1xn matrix is a row vector, and M xl matrix is a column vector. All elements of a matrix can be real or complex numbers;v-I can be written as either"i'orj' provided they are not redefined by the user A matrix is written with a square bracket '[]' with spaces separating adjacent columns and semicolons separating adjacent rows. For example, consider the following assignments of the variable x Real scalar >>x=5 Complex scalar >>x=5+10j(or >>x=5+101) [123]( Column vector >>x= [1; 2: 3] 3 matrix>>x=[123;456;789 There are a few notes of caution. Complex elements of a matrix should not be typed with spaces, i.e., -1+2j is fine as a matrix element, -1 2j is not. Also, -1+2j is interpreted correctly whereas -1+j2 is not(MATLAB interprets the j2' as the name of a variable You can always write-1+j*2 4.1 Complex number operations Some of the important operations on complex numbers are illustrated below3 Getting Help from Within MATLAB If you know the name of a function which you would like to learn how to use, use the ‘help’ command: >> help functionname This command displays a description of the function and generally also includes a list of related functions. If you cannot remember the name of the function, use the ‘lookfor’ command and the name of some keyword associated with the function: >> lookfor keyword This command will display a list of functions that include the keyword in their descriptions. Other help commands that you may find useful are ‘info’, ‘what’, and ‘which’. Descrip￾tions of these commands can be found by using the help command. MATLAB also contains a variety of demos that can be with the ‘demo’ command. 4 MATLAB Variables — Scalars, Vectors, and Matri￾ces MATLAB stores variables in the form of matrices which are M ×N, where M is the number of rows and N the number of columns. A 1 × 1 matrix is a scalar; a 1 × N matrix is a row vector, and M ×1 matrix is a column vector. All elements of a matrix can be real or complex numbers; √−1 can be written as either ‘i’ or ‘j’ provided they are not redefined by the user. A matrix is written with a square bracket ‘[]’ with spaces separating adjacent columns and semicolons separating adjacent rows. For example, consider the following assignments of the variable x Real scalar >> x = 5 Complex scalar >> x = 5+10j (or >> x = 5+10i) Row vector >> x = [1 2 3] (or x = [1, 2, 3]) Column vector >> x = [1; 2; 3] 3 × 3 matrix >> x = [1 2 3; 4 5 6; 7 8 9] There are a few notes of caution. Complex elements of a matrix should not be typed with spaces, i.e., ‘-1+2j’ is fine as a matrix element, ‘-1 + 2j’ is not. Also, ‘-1+2j’ is interpreted correctly whereas ‘-1+j2’ is not (MATLAB interprets the ‘j2’ as the name of a variable. You can always write ‘-1+j*2’. 4.1 Complex number operations Some of the important operations on complex numbers are illustrated below 4