系统仿真(MATLAB)实验2

实验二

一、实验目的：

1. Learn to design branch and loop statements program

2. Be familiar with relational and logical operators

3. Practice creating two-dimension plot

二、实验内容：

I. Assume that a,b,c, and d are defined, and evaluate the following expression.

A=20; b=-2; c=0; d=1;

1. a>b; ans =1

2. b>d; ans =0

3. a>b&c>d; ans =0

4. a==b; ans =0

5. a&b>c; ans =0

6. ~~b; ans =1

a=2; b=[1 –2;-0 10]; c=[0 1;2 0]; d=[-2 1 2;0 1 0];

7. ~(a>b) ans = 0 0

0 1

8. a>c&b>c ans =1 0

0 1

9. c<=d ??? Error using ==> <=

Matrix dimensions must agree

a=2; b=3; c=10; d=0;

10. a*b^2>a*c ans =0 11. d|b>a ans =1 12. (d|b)>a ans =0 a=20; b=-2; c=0; d=’Test’;

13. isinf(a/b) ans =0 14. isinf(a/c) ans =1 15. a>b&ischar(d) ans =1 16. isempty(c) ans =0

II. Write a Matlab program to solve the function

1()ln

1y x x

=- where x is a number <1. Use an if structure to verify that the value passed to the program is legal. If the value of x is legal, caculate y(x). If not ,write a suitable error message and quit. Solution: disp('This program solves for the value of a quadratic');

x=input('Enter the coefficient x='); if x>=1

disp('The value of x is legal!');

else

a=1/(1-x); y=log(a);

fprintf('y=%f\n',y);

end

III. Write out m. file and plot the figures with grids

Assume that the complex function f(t) is defined by the equation

f(t)=(0.5-0.25i)t-1.0

Plot the amplitude and phase of function for 0 4.t ≤≤ t=0:1:10; a=0.5-0.25*i; f=a*t-1.0;

subplot(211);plot(t,abs(f));title('amp');xlabel('t');ylabel('amp(f)');grid on;

subplot(212);plot(t,angle(f));title('phase');xlabel('t');ylabel('phas

e(f)');grid on;

IV. Write the Matlab statements required to calculate y(t) from the equation

22350

()350t t y t t t -+≥⎧=⎨

+<⎩

for value of t between –9 and 9 in steps of 0.5. Use loops and

branches to perform this calculation. a=input('Please enter t='); if a>=0

t=0:0.5:9; y=-3*t.^2+5; plot(t,y);

title('Plot of y(t)'); xlabel('t'); ylabel('y(t)'); grid on; else

t=0:-0.5:-9;

y=3*t.^2+5; plot(t,y);

title('Plot of y(t)'); xlabel('t'); ylabel('y(t)'); grid on; end t>=0

t<0

V. Write an m.file to evalue the equation

2()32y x x x =-+for all values of x between 0.1 and 3, in

steps of 0.1. Do this twice, once with a for loop and once with vectors. Plot the resulting function using a 3.0 thick dashed red line. First method: x=0.1:0.1:3; y=x.^2-3*x+2;

plot(x,y ,'b--','LineWidth',4.0); title('Plot of y(x)=x^2-3*x+2'); xlabel('x'); ylabel('y(x)');

grid on

Second method: n=1;

for x=0.1:0.1:3

y(n)=x.^2-3*x+2; n=n+1; end

x=0.1:0.1:3;

plot(x,y ,'b--','LineWidth',4.0);