366 Chapter 6. Function Reference
necessary. If intstep is not specified theintegration stepsize is determined from the
system eigenvaluesand the minimum spacing in the input signal, u.
A zero or first order discrete equivalentof the systems can be specified. The standard
Xmath *operator uses only a zero order discretization. The first order simulation
actually uses a triangle hold equivalent. This is equivalent to connecting the samples
going into the hold function. Although the continuous time hold is noncausal the
discrete state-space system is causal. This is often more accurate at higher frequencies.
Examples
# We will use trsp to simulate the output of
# a second order system for various inputs
P = 400/makepoly([1,10,400],"s")
time = [0:0.25:2]
u = gstep(time,time,[0,1,0,-1,0,1,0,-1,0])
# Examine the standard Xmath simulation
y = P*u
gph1 = ctrlplot(y);
gph1 = plot(u,gph1,{marker=1,line=0,legend=["output";"input"]})?