# MATLAB Plot

Discussion in 'Programmer's Corner' started by dbossnirvana, Jan 8, 2011.

1. ### dbossnirvana Thread Starter New Member

Dec 22, 2010
4
0
I'm trying to plot the inverse Laplace transform of

Code ( (Unknown Language)):
1.
2. >>syms s
3. >>Ys3 = (80000*s^2 + 400000*s)/(s^5 + 30*s^4 + 395300*s^3 + 11850000*s^2 + 202500000*s);
So I take this function and calculate its inverse laplace transform and I get this,
Code ( (Unknown Language)):
1.
2. >>yt3 = ilaplace(Ys3);
3. >>yt3 = sum((400000*exp(r3*t) + 80000*r3*exp(r3*t))/(4*r3^3 + 90*r3^2 + 790600*r3 + 11850000), r3 in RootOf(s3^4 + 30*s3^3 + 395300*s3^2 + 11850000*s3 + 202500000, s3))
4.
Needless to say, I'm stumped as to how I can graph this using the plot function. Because I don't know how to express the above result into something I can plot. Thus my dilemma.

Anyone knows how to get around this?

Thanks.

2. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,392
497
I would do this:
yt3=ilaplace(Ys3);
t=0:0.001:2;
plot(t, yt3);

3. ### dbossnirvana Thread Starter New Member

Dec 22, 2010
4
0
It's what I tried, but ilaplace(Ys3) outputs a symbolic expression. I'm not sure how MATLAB can recognize the "sum((400000...)) r3 in RootOf(...)" as a vectorized solution.

Has me really stumped.

Feb 19, 2010
3,392
497