MATLAB與拉氏變換s_(1)

1、MATLAB與拉氏變換X(t)f(t)ckmsyms m k cs=tf(s);G=1/(m*s2+c*s+k)()()()(22tftkxdttdxcdttxdm計算時域函數(shù)的拉氏變換計算時域函數(shù)的拉氏變換tetf2)(atetf)(atetf)(syms t a y;y=laplace(exp(a*t)y =1/(s-a)syms t a y;y=laplace(exp(-a*t)y =1/(s+a)syms t y;y=laplace(exp(-2*t)y =1/(s+2)計算時域函數(shù)的拉氏變換計算時域函數(shù)的拉氏變換atetf1)(ttetf2)(1/a*Beta(2,s/a)syms

2、t y;y=laplace(sin(t)+2*cos(t)1/(s2+1)+2*s/(s2+1)syms t y;y=laplace(t*exp(-2*t)1/(s+2)2syms t a y;y=laplace(1-exp(-a*t)tttfcos2sin)(計算時域函數(shù)的拉氏變換計算時域函數(shù)的拉氏變換syms t y;y=laplace(t*cos(3*t)*cos(3*t)*cos(3*t)3(cos)(3tttfy =-2/3/(1/9*s2+1)/(1/9*s2+9)*(7/6+1/54*s2)+4/27*s2/(1/9*s2+1)2/(1/9*s2+9)*(7/6+1/54*s2)

3、+4/27*s2/(1/9*s2+1)/(1/9*s2+9)2*(7/6+1/54*s2)-2/81*s2/(1/9*s2+1)/(1/9*s2+9)simplify(y)ans =(99*s4+3483*s2-45927+s6)/(s2+9)2/(s2+81)2計算時域函數(shù)的拉氏變換計算時域函數(shù)的拉氏變換syms t y;y=laplace(exp(-3*t)-exp(-5*t)/t)teetftt/ )()(53y =-log(s+3)+log(s+5)syms s F;F=ilaplace(-log(s+3)+log(s+5)teetftt/ )()(53計算時域函數(shù)的拉氏逆變換計算時域

4、函數(shù)的拉氏逆變換ttetf2)(1/(s2+1)+2*s/(s2+1)syms s F;F=ilaplace(1/(s+2)2)1/(s+2)2syms s F;F=ilaplace(1/(s2+1)+2*s/(s2+1)tttfcos2sin)()2)(1(1)(ssssF計算時域函數(shù)的拉氏逆變換計算時域函數(shù)的拉氏逆變換syms s F;F=ilaplace(s-1)/(s+1)*(s+2)-2*exp(-t)+3*exp(-2*t)()32()(2tueetftt計算時域函數(shù)的拉氏逆變換計算時域函數(shù)的拉氏逆變換)2)(1(3)(2sssssFsyms s F;F=ilaplace(s2+3

5、*s)/(s+1)*(s+2)Dirac(t)-2*exp(-t)+2*exp(-2*t)()22()()(2tueettftt計算時域函數(shù)的拉氏逆變換計算時域函數(shù)的拉氏逆變換syms s F;F=ilaplace(s3+5*s2+9*s+7)/(s+1)*(s+2)Dirac(1,t)+2*Dirac(t)+2*exp(-t)-exp(-2*t)23795)(223ssssssF)()2()(2)()(2tueetttftt教材教材P192，例，例4-9計算時域函數(shù)的拉氏逆變換計算時域函數(shù)的拉氏逆變換3) 1(2)(ssssFsyms s F;F=ilaplace(s-2)/(s*(s+1)3)-2+3/2*t2*exp(-t)+2*t*exp(-t)+2*exp(-t)(2)2223()(2tuttetft教材教材P194，例，例4-12計算時域函數(shù)的拉氏逆變換計算時域函數(shù)的拉氏逆變換2)