MATLAB by rudra pratap

100 Programming in MATLAB: Scripts and Functions
A script file may contain any number of commands, including those that call
built-in functions or functions written by you. Script files are useful when you have
to repeat a set of commands several times. Here is an example.
Example of a script file:
of linear equations 1 :
[ l 2r
6
r-1
Let us write a script file to solve the following system
T
2r - 1
3r
(4. 1)
or Ax = b. Clearly, A depends on the parameter r. We want to find the solution
of the equation for various values of the parameter r. We also want to find, say, the
determinant of matrix A in each case. Let us write a set of MATLAB commands
that do the job and store these commands in a file called solvex.m. How you create
this file, write the commands in it, and save the file depends on the computer you
are using. In any case, you are creating a file called sol vex . m, which will be saved
on some disk drive in some directory (or folder) .
%----------- This is the script file ' solvex . m' -----------­
% It solves equation (4.1) for x and also calculates det (A) .
A [5 2*r r; 3 6 2*r-1; 2 r-1 3*r] ; % create matrix A
b [2 ;3;5] ; % create vector b
det_A = det (A)
% find the determinant
X = A\b
% find x
In this example, we have not put a semicolon at the end of the last two commands.
Therefore, the results of these commands will be displayed on the screen
when we execute the script file. The results will be stored in variables det_A and x,
and these will be left in the workspace.
Let us now execute the script in MATLAB.
» clear all
>> r = 1;
>> solvex
% clear the workspace
% specify a value of r
% execute the script file solvex .m
det A
64
X
-0. 0312
0.2 344
1.6875
>> wh o
This is the output. The values of the
variables det_A and x appear on
the screen because there is no semicolon
at the end of the corresponding
lines in the script file.
Check the variables in the workspace.
1 If you are not familiar with matrix equations, see Section 5.1.1 on page 135.