How to plot function

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Hardik
Hardik on 29 Jul 2014
Commented: Ben11 on 30 Jul 2014
I'm working on a question where I am executing a function y = staircase(x) where
y = [ 0 if x <= 1 , 1 for 1<x<=2 & 2 if 2<x ]
So far I have;
function y = staircase(x)
for x = -3:0.01:3
if x <= 1
y = 0;
elseif x > 1 && x <= 2
y = 1;
else x > 2;
y = 2;
end
end
My question is how do I plot such a function?

Answers (3)

Ben11
Ben11 on 29 Jul 2014
A lazy way would be like this:
figure
hold on
plot((-3:0.01:1),0,(1.01:0.01:2),1,(2.01:0.01:3),2,'LineWidth',2)
line('XData',[1 1],'YData',[0 1],'LineStyle',':');
line('XData',[2 2],'YData',[1 2],'LineStyle',':');
hold off
which gives this:
Do you need to write the plotting part in your function or you simply want to look at the staircase for some other purpose?

Azzi Abdelmalek
Azzi Abdelmalek on 29 Jul 2014
Edited: Azzi Abdelmalek on 29 Jul 2014
x is an input argument, you can't assign values to x inside the function.
save this function as staircase.m
function y = staircase(x)
for k=1:numel(x)
if x (k)<= 1
y(k) = 0;
elseif x(k) > 1 && x(k) <= 2
y(k) = 1;
else x(k) > 2
y(k)= 2;
end
end
Then in Matlab Windows Command or in a new script write
x=-3:0.1:3 ; %assign values to x
y = staircase(x);
plot(x,y)
  4 Comments
Ben11
Ben11 on 30 Jul 2014
As Azzi suggested, you have to define x before you call staircase. I ran his code and it works well. Do the following:
1) Define x in the command window
x = -3:0.1:3;
2) Once this is done, you can then call staircase(x) and plot the result:
y = staircase(x);
plot(x,y)

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Star Strider
Star Strider on 29 Jul 2014
I built my own staircase function, because I didn’t want to create a separate function file.
This is how I plotted it:
x = -3:0.01:3;
staircase = @(x) [(0*(x <= 1)) + (1*((x > 1) & (x <= 2))) + (2*(x > 2))];
sc = staircase(x);
figure(1)
plot(x, sc)
axis([xlim -0.5 2.5])
The axis call makes it visible over its range.

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