Graph plot always appears as a straight line

Hi, I don't know how to fix this. y graph looks like a straight line instead of an exponential curve. Please help me.. thanks a lot in advance !

l=0.5;
i=22/7;
v=0.8;
p=0.1;
x=[0:0.2:1.0];
y=(p*r^4*x)/(8*v*l);
plot(x,y)

[Stephen23]

What is r ?

Your function of x looks linear because it is linear in x:

y=(p*r^4*x)/(8*v*l);
%        ^ independent variable

The independent variable x is to the power 1, which is linear. I don't see why you expect a non-linear curve from power 1.

[Abhinandana R]

sir actually I need a graph that looks like a curve for the following equation

I'm new to this software sir. I tried the above coding as per my knowledge. This equation is a function of r sir(y varies according to r). so now ,can we draw a graph that looks like a curve? if yes, kindly suggest me the coding sir. it will be helpful for my project work sir and we can give any values to the variables r, x, u and l.

[Stephen23]

"y varies according to r"

But what you calculated is y varing with x.

[Abhinandana R]

ok sir.. now I got it. but how can I change it ?

[madhan ravi]

see Rik Wisselink’s answer below

Answer 1

[Rik]

You are varying x, instead of r. The code below shows how you could edit your code to plot y as a function of r.

l=0.5;
i=22/7;
v=0.8;
p=0.1;
x=0.1;
n_r_steps=100;
r=linspace(0,1,n_r_steps);
y=(p*r.^4*x)/(8*v*l);
plot(r,y)

[Abhinandana R]

thanks a lot sir. but it gives the value in the command window instead of graph.

I need a graph for the below equation sir. can you suggest a coding for this??

[Rik]

If you run this code, it will plot the graph in the current axis. If it does not exist, it will create one.

I don't know how you would manage to have this make any output in the command window, unless you have a variable with the name plot.

[Abhinandana R]

I was totally blank of this software sir. but now somehow I got cleared and I got the expected graph sir. thanks a lot !

Answer 2

[Kevin Phung]

if r is a constant, you will get a straight line. if r varies, then you will get a curve.

also, you may want to add a period before your raising to a power and multiplcation for non-scalars.

so .^ and .*