Can I call this plot as Contour plot?

Hello all,

Refer to the code below

clear all;

x=sin(2*pi*1000*((0:0.1:200)/10000));
y=cos(2*pi*1000*((0:0.1:200)/10000));
figure
plot(x,y)
xlabel ('Values of Sine');
ylabel('Values of Cos');

Can I call the plot I obtain as "Contour plot of x & y" ? What plot it is exactly?

Answer 1

[Matt Tearle]

What you're doing is called a parametric plot - x(t) against y(t) for a parameter variable t.

[Raviteja]

then when a plot is called contour plot?

[Matt Tearle]

A contour plot is a method for visualizing a scalar function of two variables: z = f(x,y). The contours are curves defined by setting z equal to a fixed value: f(x,y) = c

You can use a contour plot to visualize an implicitly-defined function f(x,y) = c by looking for just the single contour at level c.

[Raviteja]

Thank Matt,

For the given sine and cos wave, can you give an example of contour plot in matlab.You take any simple example to explore the above concept you told.

Thanks for this.

[Jiro Doke]

Have you looked at the documentation for "contour"? It has a couple of examples.

http://www.mathworks.com/help/matlab/ref/contour.html

[Matt Tearle]

Ok, so x^2 + 2y^2 = 5 is an equation for an ellipse. Two ways to plot this in MATLAB:

Parametrically

t = linspace(0,2*pi);

x = cos(t)*sqrt(5);

y = sin(t)*sqrt(5/2);

plot(x,y)

Using contours

[x,y] = meshgrid(linspace(-2.5,2.5));

z = x.^2 + 2*y.^2;

contour(x,y,z,[5 5])

Answer 2

[Sean de Wolski]

Sure:

%your stuff followed by:
title('Contour plot of x & y');

[Matt Tearle]

::rimshot:: Thank you, you've been great. Don't forget to tip your waiter.