MATLAB绘制图像以及基本运算

1.Sa(t)函数的画法（代码与图如下）：

t =-4*pi:0.01:4*pi;
ft=sin(t)./t;
plot(t,ft);

2.信号的平移，尺度变换，反褶等

t=-2:0.01:1;

y=1*(t>=(-2) & t<=(0))+(-1*t+1).*(t>(0) & t<=(1));

plot(t,y);

axis([-2 1 -1 2])

t1=t+2;

t2=t/3;

t3=-t;

t4=-(t+2)./3;

subplot(321),plot(t,y),axis([-2 1 -1 2]),xlabel('f(t)');

subplot(322),plot(t1,y),axis([0 3 -1 2]),xlabel('f(t-2)');

subplot(323),plot(t2,y),axis([-1 1 -1 2]),xlabel('f(3t)');

subplot(324),plot(t3,y),axis([-1 2 -1 2]),xlabel('f(-t)');

subplot(325),plot(t4,y),axis([-1 1 -1 2]),xlabel('f(-3t-2)');

3.信号运算之求导以及积分

syms  x a;

A=diff(x*sin(x)*log(x),'x',1);

b=int(x.^5-a*x.^2+sqrt(x)./2,'x');

c=int(x*exp(x)./(1+x).^2,'x',0,1);

结果分别为：

A=sin(x) + log(x)*sin(x) + x*cos(x)*log(x)

b=x^(3/2)/3 - (a*x^3)/3 + x^6/6

c=exp(1)/2 - 1

4.信号的卷积之符号运算法：

syms tao;

t=sym('t','positive');

xt1=sym('heaviside(t)-heaviside(t-1)');

xt2=sym('heaviside(t)-heaviside(t-3)');

xt_tao=subs(xt1,t,tao)*subs(xt2,t,t-tao);

yt=int(xt_tao,tao,0,t);

yt=simplify(yt);

ezplot(yt,[0,2]);grid on;

注意：此处是门函数的卷积

5.信号卷积之数值求解法：

dt=0.01;

t=0:0.01:5;

n=length(t);

f1=( t>=0 )-( t>=2 );

f2=( t>=0 ) + ( t>=1 )-( t>=2 )-( t>=3 );

f=conv(f1,f2)*dt;

tt=(0:n-1)*dt;

subplot(221),plot(t,f1);

subplot(222),plot(t,f2);

subplot(223),plot(t,f);