Write a program using MATLAB only

ECE 115, Sp/13 Introduction to Electrical and Computer Engineering

MATLAB Homework #1

Due in class: Friday, 2/15/13

For this MATLAB homework, you must provide a statement of the assignment, a print out of your program and a print out of the results. Add comments wherever appropriate. 1) Write a program to obtain samples of: 1 ( ) 0.9 cos(1400 / 3)x t tπ π= + ,

2 ( ) 0.9 cos(400 / 4)x t tπ π= − , and 3 1 2( ) ( ) ( )x t x t x t= over a 4 sec time range. Use a sample time

increment T given by 1 / sT f= , where 44100sf = samples/sec. Then, use the MATLAB function sound to hear all three signals. Provide plots of the first 1000 points of each signal. See sample programs posted on the blackboard. The pitch (frequency) of x1(t) is 700 Hz. What is the pitch of x2(t)? Describe what x3(t) sounds like. 2) Write a program to solve the following equations for , , ,b z w and y .

2 2 13 2 3 7 8 0

4( ) 8( 3 ) 4 6 7( 4 ) 3

y z w b b z w y

b y z w w b z

− + − = − + − − + =

− − + = − + = −

Include in your program MATLAB statements that check that your solution is correct. For example, give y - 2z + w - 2b - 13. 3) Consider the power series ( )y x given by

(2 1) 3 5 7

0 ( ) ( 1)

(2 1)! 3! 5! 7! kK

k

k

x x x xy x x k

+

= = − = − + − +

+∑  Write a program to find and plot y versus x for x values over the range 0 2x π≤ ≤ . Do this for

5K = and 50K = . Use 201N = points for x .