- #1
rootX
- 478
- 4
matlab:
>> ilaplace(exp(-1*s)/(s+3)^3)
ans =
1/2*heaviside(t-1)*(t-1)^2*exp(-3*t+3)
But I think there should be an additional exp(3) multiplied by all.
=exp(-1*s)/(s+3)^3
=exp(-1*(s+3)+3)/(s+3)^3
Taking out exp(-3t). In above step I did (s+3)+3 because exp(-3t) says all variables should be shifted by 3 ..
=[exp(-1*(s)+3)/(s)^3]*exp(-3t)
Now I take care anything but Heaviside
=[exp(-1*(s))]*exp(-3t)*[t^2/2]*exp(3)
now I take care of Heaviside
=exp(-3(t-1))*[(t-1)^2/2]*exp(3)
I might have made some error while explaining what I was doing - just ignore it. But, the thing I am concerned about is the one in red. It gives me exp(3) in the end which MATLAB does not.
Thanks
>> ilaplace(exp(-1*s)/(s+3)^3)
ans =
1/2*heaviside(t-1)*(t-1)^2*exp(-3*t+3)
But I think there should be an additional exp(3) multiplied by all.
=exp(-1*s)/(s+3)^3
=exp(-1*(s+3)+3)/(s+3)^3
Taking out exp(-3t). In above step I did (s+3)+3 because exp(-3t) says all variables should be shifted by 3 ..
=[exp(-1*(s)+3)/(s)^3]*exp(-3t)
Now I take care anything but Heaviside
=[exp(-1*(s))]*exp(-3t)*[t^2/2]*exp(3)
now I take care of Heaviside
=exp(-3(t-1))*[(t-1)^2/2]*exp(3)
I might have made some error while explaining what I was doing - just ignore it. But, the thing I am concerned about is the one in red. It gives me exp(3) in the end which MATLAB does not.
Thanks