MATLAB by rudra pratap

112 Programming in MATLAB: Scripts and Functions
idea to copy the function definition line without the word function among those
first few comment lines so that the execution syntax of the function is di::>played
by the on-line help. The command lookfor looks for the argument string in the
first commented line of M-files. Therefore, in keeping with the somewhat confusing
convention of MATLAB's built-in functions, you should write the name of the script
or function file in uppercase letters, followed by a short description with keywords
as the first commented line. Thus, the first line following the function definition
line in the example function on page 104, Section 4.2.1, reads
% SDLVEXF solves a 3x3 matrix equation with parameter r .
4.3.2 Continuation
An ellipsis (three consecutive periods) . at the end of a line denotes continuation. So,
if you type a command that does not fit on a single line, you may split it across two
or more lines by using an ellipsis at the end of each but the last line.
Examples:
A = [1 3 3 3; 5 10 -2 -20 ; 3 5
10 2; 1 0 0 9] ;
x = s in (linspace ( 1,6*pi , 100)) ·* cos(linspace (1,6*pi ,100) ) + . ..
0.5*ones (1,100) ;
plot (tube_length ,fluid_pressure , ' :' , tube _length , . . .
theoretical_pressure ,'-')
(The last command assumes that variables tube_length, fluid_pressure, etc.
exist in the workspace.)
You may not, however, use continuation inside a character string. For example,
typing
logo 'I am not only the President and CEO of Miracle Hair , . ..
but also a client' ;
produces an error. For creating such long strings, break the string into smaller
string segments and use concatenation (sec Section 3.3).
4.3.3 Global variables
It is possible to declare a set of variables to be globally access.ible to all or some
functions without passing the variables in the input list. This is done with the
global command. For example, the statement global x y z declares the variables
x, y, aml z Lo be glulml. This statement goes before /l,llY executable otatement in
the functions and scripts thaL uecd to access the values of the global variables. Be
can'!fnl with the names of the global variables. It i:'l generally 11 good idea to name
such variables with long strings to avoid any unintended match with vLher local
variables.
Hxample: Consider solving the following first-order ODE:
x = kx + csin t, x(O) = 1 .0