Thanks a lot David, this is what I needed.
Just if somebody else might need it, i will resolve the problem:
# declare t and tau as symbolic variables
var('t')
var('tau')
# monoexponential equation
g(t) = e**(-t/tau)
# 2-piece result (one from 0 to t0, the second from t0 to 1000
t0 = 0.2 # this is the onset of the exponential function
MNTB_g = piecewise([[(0,t0),lambda t:0],[(t0,1000),g.subs(tau=0.9)]])
# plots!
fig = list_plot([MNTB_g(t) for t in xrange(1000)], plotjoined = True,
rgbcolor='red')
fig.show(xmax=25)
The figure looks a little weird though, I guess I would have to solve it
analytically.
Thanks a lot for your help
Jose.
David Joyner wrote:
Use Piecewise. Type Piecewise? For examples.
On Tuesday, March 16, 2010, Jose Guzman <n...@neurohost.org> wrote:
Hi everybody,
i was wondering, which is the best method to plot a conditional function within
an interval. For example, a function whose values are:
0 if t<t0
f(t) if t>t0
where f(t) is a simple monoexponential decay that starts at t0. I tried the
following in Sage:
t = var('t')
def f(t,t0):
if t<t0:
return 0
else:
return e**(-(t)/tau)
Now if I plot
plot(f(t,t0=0.5,tau=0.05,0,1,rgbcolor='red')
The plot starts at t=0 and unfortunately the function f(t) too!
Is there any better way to define a conditional function with Sage?
Thanks a lot in advance.
Jose.
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