How to graph equations with different x domains?

Suppose I have two equations:

x(t)= -10000e^(-0.05t) + 10000.......(1) where 0<=t<=26

x(t)= -5123.635e^(-0.05t) + 10000.......(2) where 26<=t<=100

How do graph these two equations on the same window ?

I tried to use the hold on hold off function but im failing to do it. Is there any other way to do it? Im a beginner so easy codes please ;)

Answer 1

[Star Strider]

First, code it correctly, then use logical indexing —

t = linspace(0, 110);
x1 = @(t) -10000*exp(-0.05*t) + 10000;
x2 = @(t) -5123.635*exp(-0.05*t) + 10000;

v1 = ((t>=0) & (t<=26));
v2 = ((t>=26) & (t<=100));

figure
plot(t(v1), x1(t(v1)))
hold on
plot(t(v2), x2(t(v2)))
hold off
grid

.

[Muhammad Faaz Usman]

Hello, I tried to use your code. However no figure pops up. I tried to use some older functions i graphed earlier and now they are also not popping up. What happened so suddenly?

[Star Strider]

I have no idea what the problem could be.

I ran my code in the Answer window using the green ‘Run’ arrow, and also initially offline, on the computer I’m using now. The code ran correctly both times.

Running it again here —

t = linspace(0, 110);
x1 = @(t) -10000*exp(-0.05*t) + 10000;
x2 = @(t) -5123.635*exp(-0.05*t) + 10000;

v1 = ((t>=0) & (t<=26));
v2 = ((t>=26) & (t<=100));

figure
plot(t(v1), x1(t(v1)))
hold on
plot(t(v2), x2(t(v2)))
hold off
grid

And it again works correctly.

[Muhammad Faaz Usman]

Yes it has worked. I have tweaked the code as per the question. Now i want to connect the two curves with a curved line to show the decay. How do I go about that?

t = linspace(0, 110);
x1 = @(t) -10000*exp(-0.05*t) + 10000;
x2 = @(t) -5123.635*exp(-0.05.*(t-34)) + 10000;
v1 = ((t>=0) & (t<=26));
v2 = ((t>=34) & (t<=100));
figure
plot(t(v1), x1(t(v1)))
hold on
plot(t(v2), x2(t(v2)))
hold off
grid

[Star Strider]

I would do something like this —

t = linspace(0, 110);
x1 = @(t) -10000*exp(-0.05*t) + 10000;
x2 = @(t) -5123.635*exp(-0.05*t) + 10000;
v1 = ((t>=0) & (t<=26));
v2 = ((t>=26) & (t<=100));
ofst = min(x2(t(v2)))-max(x1(t(v1)))

ofst = 1.4360e+03

figure
plot(t(v1), x1(t(v1)))
hold on
plot(t(v2), x2(t(v2))-ofst)
hold off
grid

That is likely as close as it is possible to match them. Even though the both have 26 in common, the small reminaing gap is caused by the resolution of ‘t’.