MatLab Lab#1 in Differential Equation course

SAMPLE QUESTION: Exercise 1: Consider the function

f (x,C)= sin(C x) Cx

(a) Create a vector x with 100 elements from -3*pi to 3*pi. Write f as an inline or anonymous function

and generate the vectors y1 = f(x,C1), y2 = f(x,C2) and y3 = f(x,C3), where C1 = 1, C2 = 2 and

C3 = 3. Make sure you suppress the output of x and y's vectors. Plot the function f (for the three

C's above), name the axis, give a title to the plot and include a legend to identify the plots. Add a grid to the plot.

(b) Without using inline or anonymous functions write a function+function structure m-file that does the same job as in part (a)

SAMPLE LAB WRITEUP:

MAT 275 MATLAB LAB 1 NAME: __________________________ LAB DAY and TIME:______________ Instructor: _______________________ Exercise 1 (a)

x = linspace(-3*pi,3*pi); % generating x vector - default value for number % of pts linspace is 100 f= @(x,C) sin(C*x)./(C*x) % C will be just a constant, no need for ".*" C1 = 1, C2 = 2, C3 = 3 % Using commans to separate commands y1 = f(x,C1); y2 = f(x,C2); y3 = f(x,C3); % supressing the y's plot(x,y1,'b.-', x,y2,'ro-', x,y3,'ks-') % using different markers for % black and white plots xlabel('x'), ylabel('y') % labeling the axis title('f(x,C) = sin(Cx)/(Cx)') % adding a title legend('C = 1','C = 2','C = 3') % adding a legend grid on

Command window output:

f =

@(x,C)sin(C*x)./(C*x)

C1 =

1

C2 =

2

C3 =

3

(b) M-file of structure function+function

function ex1 x = linspace(-3*pi,3*pi); % generating x vector - default value for number % of pts linspace is 100 C1 = 1, C2 = 2, C3 = 3 % Using commans to separate commands y1 = f(x,C1); y2 = f(x,C2); y3 = f(x,C3); % function f is defined below plot(x,y1,'b.-', x,y2,'ro-', x,y3,'ks-') % using different markers for % black and white plots xlabel('x'), ylabel('y') % labeling the axis title('f(x,C) = sin(Cx)/(Cx)') % adding a title legend('C = 1','C = 2','C = 3') % adding a legend grid on end function y = f(x,C) y = sin(C*x)./(C*x); end

Command window output:

C1 =

1

C2 =

2

C3 =

3