Why won't this function plot?

For some reason I can't plot this function.

t=0:30;

c1_exp = b1*exp(-a1*t) + b2*exp(-a2*t);

All variables except for t are constants.

I've tried

fplot(c1_exp, 'g-', 'Linewidth', 3)

and

for ii= 1:30

plot(c1_exp(:,ii))

end

Nothing happens but I don't get any error messages.

What am I doing wrong?

[Steven Lord]

What are the magnitudes (or the actual values) of your coefficients? If the value inside the exp calls gets too small, the exponential would underflow to 0.

exp(-750) % underflow

ans = 0

So if your a values were on the order of say 1000 only the points with t = 0 could possibly plot.

a = 1000;
t = 0:10;
y = exp(-a*t)

y = 1×11

1 0 0 0 0 0 0 0 0 0 0

Answer 1

[Simon Chan]

No need to use the for loop, Just use the following:

plot(c1_exp)

[AUSTIN WHITELEY]

that doesn't work

[Voss]

Are one or more of the constants NaN?

Answer 2

[Voss]

Try

plot(c1_exp)

or

plot(t,c1_exp)

With your for loop, you're plotting one data point at a time, which is impossible to see without a data marker. And fplot() is for plotting with a function handle, e.g.,

fplot(@(t) b1*exp(-a1*t) + b2*exp(-a2*t))